U.S. intelligence officials told senators yesterday that Iraqi President Saddam Hussein has a hard core of professional, disciplined terrorists scattered around the world, waiting for his orders to strike.

Sen. David L. Boren (D-Okla.), chairman of the Senate intelligence committee, said after a two-hour briefing that such orders have yet to come through, but that U.S. officials are convinced that Saddam still intends to "expand the battle" worldwide.

"Saddam has put in place a network involving some of the most sophisticated terrorist organizations in the world," Boren said. He said they are "pretty highly controlled, pretty highly disciplined."

Boren and the committee vice chairman, Sen. Frank H. Murkowski (R-Alaska), said anti-American attacks in the first days after the U.S. offensive against Iraq have been fewer than expected.

"Terrorist attacks around the world so far have been more or less amateur groups traditionally hostile to the United States," Boren said. "We have not seen the wave of terrorism from professional organizations that we thought we might see. . . . The disciplined terrorists, we know that some of them have been waiting anxiously to get those orders."

Boren said possible explanations are that Saddam and his top officials were stunned by the extent of the first attack, that the Iraqi command structure was too shaken up, or that Saddam never intended to act this quickly. Some counterterrorism experts think the Iraqi leader is holding back deliberately and that the dangers of terrorism, as acts of revenge, will grow with the war's length and could become worse after the war ends.

"Terrorism is a weapon of desperation," said French expert Xavier Raufer. "He won't use it now."

Nevertheless, Baghdad radio this morning broadcast a call for terrorism against the "interests, facilities, symbols and figures" of the United States, Britain, France, the Netherlands, Saudi Arabia, the followers of the emir of Kuwait and their allies, the Associated Press reported from Nicosia, Cyprus, where the broadcast was monitored. The Iraqi statement said Moslems had "a sacred duty to grasp this historic opportunity."

Early this morning, the State Department warned Americans that it has received reports of a "credible threat involving possible terrorist activity in Bangkok" in the next 48 hours. It said U.S., British, Israeli and Australian installations and U.S. and European airlines are particularly threatened.

The department said it has "no information that a specific flight has been targeted," adding that all airlines that fly to Bangkok are cooperating in heightening security.

Paul Wilkerson, director of the London-based Research Institute for the Study of Conflict and Terrorism, said he expects "a much more intensive level" of terrorist violence after military hostilities end. After the 1967 war in the Middle East, the Yom Kippur War of 1973 and the 1982 war in Lebanon, "we saw a backlash by terrorist groups to avenge the humiliating defeats, inflicted on them by the Israelis in each case," he said.

Neither Boren nor Murkowski identified the terrorist cells reportedly awaiting Saddam's orders, but former U.S. officials and others say they belong primarily to the Abu Nidal Organization (ANO), a violent Palestinian group.

"I don't think we're dealing with a terrorist army, but a small group of highly trained people who can do a lot of damage," Wilkerson said. "Saddam has been building links with terrorist organizations for many months, so the possibility of giving them the backup of Iraqi secret services and diplomatic assets is quite real."

The ANO -- whose leader, Sabri al Banna, was in Baghdad in recent months and set up a small staff there -- has had a "rudimentary infrastructure" in the United States for several years, according to former CIA counterrorism expert Vincent Cannistraro, now with the National Strategy Information Center here.

Boren said FBI agents "have under {domestic} surveillance any groups about which we have any shred of evidence they might act," indicating that foreign intelligence agencies are keeping close watch overseas in cooperation with the CIA. He and Murkowski said there is a "very real" threat of terrorism in the United States. But it is considered much less likely here than in the Middle East, Europe and other parts of the world such as the Philippines.

Thomas E. DuHadway, special agent in charge of the FBI's Washington field office, said, "There is no terrorist infrastructure or groups in this area."

Murkowski voiced concern about the estimated 3,000 Iraqis in the United States with expired visas and said he thought it important for the FBI "to find out why they are still here."

Anti-American demonstrations and protests took place in Germany, Australia, Japan, New Zealand and Algiers. The most serious incident was in Jakarta, Indonesia, where a bomb was found on the grounds behind the home of John Monjo, the U.S. ambassador. It was detonated by a police bomb squad.

In a suburb of Santiago, Chile, small bombs exploded Thursday night at branches of two U.S. banks, but caused little damage.

In Detroit, Mayor Coleman Young (D) declared a "state of emergency" to get the Michigan National Guard's help in securing Canadian-U.S. border crossings. Young said he knew of no immediate terrorist threat but wanted the Guard units to take pressure off the city's understaffed police department.

In another development, the Peace Corps this week pulled its volunteers out of Morocco, Tunisia and Mauritania, a Moslem country in northwest Africa sympathetic to Iraq, for security reasons.

Staff writer Sharon LaFraniere in Washington and special correspondent Lauren Ina in Detroit contributed to this report.