In August last year, U.S. intelligence agents learned that Osama bin Laden's al Qaeda terrorist network had obtained a highly detailed, hand-drawn map of the U.S. diplomatic compound here.

The discovery stoked immediate fears of a U.S. Embassy bombing akin to those in Kenya and Tanzania in 1998. But it also provided one of the first indications that al Qaeda was focusing attention on Indonesia, the Southeast Asian country that is home to more Muslims than any other nation.

Since the Sept. 11 attacks on New York and the Pentagon, signs of al Qaeda activity in Indonesia have multiplied. U.S. and Indonesian intelligence officials say they believe that hundreds of foreigners who may be linked to al Qaeda and coming from as far away as Europe visited a secret training camp last year in the jungles of Sulawesi, an island in central Indonesia.

The leader of the country's largest and most-violent Muslim militia has acknowledged to police that he was offered financial backing by a bin Laden aide. And intelligence officials said they have identified links between bin Laden and a prominent Muslim cleric who heads a paramilitary group.

U.S. officials also have become increasingly concerned that some al Qaeda members may have established "sleeper cells" in Indonesia that could become operational now that many of the group's leaders in Afghanistan have been forced into hiding, captured or killed.

But despite such clues, U.S. and Indonesian officials said they still are struggling to ascertain the scope of al Qaeda's operations in Indonesia and the network's connections with indigenous extremist groups. "We know they're here," a senior Indonesian intelligence official said. "We just haven't found them."

The prospect of significant al Qaeda activity in Indonesia has prompted the Bush administration to put Indonesia on a short list of nations to focus on as the U.S.-led campaign against terrorism expands beyond Afghanistan. "Going after al Qaeda in Indonesia," Deputy Defense Secretary Paul Wolfowitz said recently, "is not something that should wait until after al Qaeda has been uprooted from Afghanistan."

In many ways, Indonesia is an easy place for terrorist groups to operate. Composed of more than 17,000 islands, it has some of the world's most porous borders. Law enforcement and banking regulations are lax. Guns and explosives are easy to purchase.

Indonesia also is home to several radical Muslim groups, which want the officially secular nation to adopt rigid Islamic laws. Although most Indonesians do not support the local militants, the strength of the groups has mushroomed in recent years, fueled in part by increasing poverty and a surging interest in fundamentalist Islamic theology.

The local groups "have created a very conducive host environment for foreign terrorists," a U.S. official said. "There is already an infrastructure here for them to plug into."

A sectarian conflict in the Moluccas islands, where for three years Muslim militants have been waging a jihad, or holy war, against Christian villagers, provides foreign trainees exposure to fighting. "Indonesia offers practical jihad experience you can't get in too many other places," a senior U.S. official said.

Indonesian police and military officials have publicly denied that foreign terrorist groups have set up training camps in the country. But privately, intelligence and government officials said they believe al Qaeda operatives ran a makeshift training facility on Sulawesi last year. The camp, officials said, was located in dense jungle near the port city of Poso, which has been riven by religious fighting.

The officials said the camp, a collection of ramshackle huts where recruits were taught how to use automatic weapons and build bombs, was operated by al Qaeda members with the assistance of local Muslim militants. Unlike other paramilitary training facilities in Indonesia, a country where political groups often have armed wings, this camp was a well-kept secret, officials said.

"This one was different," one official said. "It was by foreigners, for foreigners."

Indonesian intelligence officials estimated that over the past year several hundred people, many of them from Europe, Pakistan and the Middle East, entered the country posing as aid workers to reach the camp.

The officials said that in August and October, police officers briefly detained several non-Indonesians traveling in the Poso area, but they were released after showing local officials a letter from a Muslim charity based in southern Sulawesi stating they were going to Poso to help rebuild mosques.

A senior Indonesian intelligence official said investigators subsequently discovered that the charity, known as the Crisis Prevention Committee, had "connections to Osama bin Laden and al Qaeda." Police have concluded the foreigners were probably going to or from the camp when they were detained.

The senior official said intelligence agents began looking for the camp after authorities in Spain passed along evidence that had been obtained in the investigation of eight suspected al Qaeda members arrested in November. The evidence indicated that hundreds of foreign fighters had traveled to the Poso area for training last year.

A Spanish court indictment identified a 34-year-old Indonesian man, Parlindungan Siregar, who studied aeronautical engineering in Spain in the 1990s, as a key organizer of the training missions. Spanish authorities have alleged that he is affiliated with the Laskar Jihad, the Muslim militia leading the fight in the Moluccas and in Poso to evict Christians and implement Islamic law.

The indictment called Siregar, whose phone number was found in address books belonging to two of the eight suspects, a "leader of one of the camps in that country in service to Osama bin Laden."

The senior Indonesian intelligence official said agents have not yet found Siregar or others allegedly involved in conducting the training, but they have identified the location of the camp, which they said is no longer operational. "They probably closed it down after the arrests in Spain," the official said. "We're keeping a watch on it. If they come back, we will go in and arrest them."

A Laskar spokesman said the group has not trained non-Indonesian fighters, but he acknowledged that some "foreign volunteers have helped with humanitarian work."

The leader of the Laskar Jihad, Jaffar Umar Thalib, has denied that his organization has links to al Qaeda.

Jaffar has told police and local journalists that he met bin Laden in Pakistan in 1987 as they both were preparing to enter Afghanistan to fight against invading Soviet forces. Jaffar said he was quickly turned off by bin Laden's wealth and what he thought was bin Laden's poor grasp of Islam. Jaffar said he opposes bin Laden's use of suicide bombers.

In July, bin Laden sent an emissary to the Moluccas to offer financial support to the Laskar Jihad and to urge the group to join the al Qaeda network, Jaffar said. He said he refused.

The envoy, Jaffar said, was accompanied by members of another group, Laskar Mujaheddin, which also is attacking Christian villagers in the Moluccas and on Sulawesi. Indonesian intelligence officials said the leader of the Laskar Mujaheddin, a prominent Muslim cleric named Abubakar Baasyir, has long-standing ties to bin Laden.

Officials said he sent a letter to dozens of hard-line Muslim clerics in Indonesia and Malaysia in 1998, after the U.S. embassy bombings in Africa, saying that bin Laden wanted them "to prepare for a jihad against Americans." The letter concluded by offering the clerics a chance to meet bin Laden "through the safest way."

Baasyir denies he has connections to bin Laden, but he does not condemn the tactics the Saudi-born fugitive employs. "America has declared war on Islam," he said during an interview at a large religious school that he runs on the main Indonesian island of Java. "Planting bombs, suicide attacks, that's part of war."

U.S. and Indonesian officials said they suspect al Qaeda is associated with both Laskar Jihad and Laskar Mujaheddin, but they lack evidence to make a conclusive link.

A U.S. official said it remains unclear whether significant numbers of al Qaeda operatives remain in Indonesia. "We know they have come and gone, and it seems clear they'll be back again," the official said. "But are they here now? Have they set up sleeper cells here? We still are not sure."

Discovery of the hand-drawn map of the U.S. diplomatic compound was confirmed by U.S. officials, who declined to give a full account of the incident, citing national security concerns. After the map was found, already-tight security at the embassy was increased and U.S. counterterrorism experts mounted an intense investigation into who might be planning an attack, but their efforts yielded no definitive suspects, officials said.

The map's existence added to fears for the compound's security in October, after the United States began its bombing campaign in Afghanistan. Thousands of protesters besieged the embassy, causing the State Department to evacuate nonessential diplomatic personnel from the country.

"The map really freaked people out," said a U.S. official. "It made people recognize, for the first time, that al Qaeda was serious about Indonesia."

The lack of firm intelligence about al Qaeda is one of the key challenges facing the United States as it attempts to broaden its campaign against terrorism.

For years, Western spy agencies paid little attention to Indonesia as a potential base for international terrorists. The country's intelligence services also failed to collect information, because they were distracted by separatist rebellions and almost four years of political turmoil in the capital, Jakarta.

Indonesia's economic woes hampered what little intelligence-gathering was attempted. The government cannot afford equipment that is standard in many countries, including devices to tap mobile phones, the senior Indonesian intelligence official said. "How can we pursue these guys if we can't even listen to their phone calls?" the official said.

Even if details of al Qaeda's operations in Indonesia become clearer, pursuing terrorists in this conflict-racked country of 220 million could prove vexing.

Unlike Somalia or Iraq, Indonesia has a friendly relationship with the United States, making unilateral military action by Washington highly unlikely. Cooperating with local forces, as the United States is doing in the Philippines, also is doubtful because of a U.S. law, passed in the wake of the Indonesian army's human-rights abuses in East Timor, that prevents military assistance to Indonesia.

U.S. military officials have said the law should be rescinded in the interest of the war on terrorism. Efforts to overturn the amendment failed last month, but the Pentagon did win the right to provide anti-terrorist training to the Indonesian military this year.

U.S. officials also have quietly expanded the scope of intelligence about terrorist-related issues that is shared with Indonesia, with the hope that it might spur police and military leaders to take more aggressive steps to crack down on extremist groups. But the effort has received a mixed reception.

Although some officials in Jakarta want to rein in such groups as Laskar Jihad, many others are reluctant, fearing a crackdown could spark retaliation by the groups and alienate conservative Muslim political parties that are part of President Megawati Sukarnoputri's ruling coalition.

"Our American friends need to understand that we are in a very difficult position," the senior Indonesian intelligence official said. "These groups are our enemy. They are hurting us and we want to hurt them back. But we need to take careful steps. If we approach it the wrong way, our government can be toppled."

Men carry makeshift rifles through Poso, a violence-riven Indonesian city where officials believe al Qaeda ran a training camp.