Security forces in Europe and Asia have stepped up efforts in the last week to counter Iraqi-sponsored terrorism with a wave of diplomatic expulsions, preemptive roundups and deportations of "undesirables."

In Britain, authorities have even set up a prisoner-of-war camp at Salisbury Plain, where the first detainees will be 33 Iraqis who were admitted to Britain to study.

France not only booted out most of Iraq's diplomats but also deported 16 pro-Iraqi activists of various nationalities on grounds they represented potential support links for terrorist groups.

Italian police raided a former bakery in Rome where about 2,000 immigrants had taken temporary shelter and picked up 1,600 of them -- mostly Pakistanis and north Africans -- for questioning.

The moves are aimed at breaking up what Western intelligence agencies say is a global network of potential terrorist cells that in the past has helped Iraq's intelligence services conduct espionage, harass outspoken exiles and support Iraq's weapons development and covert technology-procurement efforts.

Terrorist attacks against U.S. and allied targets since the Persian Gulf War began have been limited so far largely to what one former CIA official described as "bombs and bells in the middle of the night," causing only property damage. The incidents, another expert said, appear largely the work of "local, primarily left-wing groups taking the occasion to express themselves."

An anti-tank missile was fired at an American Express Bank branch in Athens early today, damaging an office, and a bomb blast shook a Greek-owned insurance company building, authorities said. No one was injured in either attack and no one asserted responsibility, the Associated Press reported.

"We haven't seen the real tough stuff yet," said Vincent Cannistraro, former chief of counterterrorism operations at the CIA. Right now, he said, "everybody and his brother is just taking advantage of the Persian Gulf to go out and do what they want to do anyway."

U.S. intelligence officials said last week that much worse is expected. They said a major terrorist training course was conducted in or around Baghdad last month in the arts of airplane hijacking and bombing. The class was reportedly composed of Iraqis and Palestinians. Suicide missions, the officials warned, are quite possible.

CIA officials, a government source said, believe that allied air attacks on Iraqi President Saddam Hussein's command and control facilities may have temporarily cut off Baghdad's ability to give orders to Iraqi agents. Other analysts said Western governments may have effectively disrupted terrorist operations by systematically deporting Iraqi diplomats. Banished in the process, experts say, are many members of Iraqi intelligence.

"If you really wanted to impair their ability to operate, you would reduce their numbers {at Iraqi embassies} to a minimum, down to two or three people," said Brian Jenkins, senior managing director of Kroll Associates, an international investigative firm.

Direct involvement of Iraqi diplomats in terrorist operations was not anticipated before the U.S.-led air attacks. Many experts predicted that Saddam's summons to a holy war against imperialist targets would be answered by operatives without any clear connection to Baghdad.

The bungled bombing of a U.S. government cultural center in Manila recently shattered that impression. One Iraqi was killed and another wounded when the bomb went off prematurely. The investigation of the Jan. 19 explosion implicated two Iraqi diplomats, allegedly Iraqi intelligence agents, and two Iraqi students, brothers whose father is the Iraqi ambassador to Somalia.

Another close call involved the U.S. ambassador in Jakarta. His gardener found a bomb hidden in the garden. According to Sen. Frank Murkowski (R-Alaska), vice chairman of the Senate intelligence committee, the gardener "noticed that the flowers had been rearranged."

In the United States, officials of the Federal Bureau of Investigation have consistently said they believe they have the situation under control. "I think we're in good shape" to deal with a terrorist threat, FBI director William S. Sessions said yesterday on NBC's "Meet the Press."

FBI officials, including Sessions, acknowledge that a rudimentary terrorist infrastructure exists in this country. Officials said it is controlled primarily by the deadly Abu Nidal organization. But FBI agents have conducted intensive surveillance since the Aug. 2 invasion of Kuwait, and recently, sources say, they have been making "house calls" on those they have been watching.

"They're not shaking people down," one source said, "but they're at least letting people know, 'Look, we know who some of you are, and we're watching.' "

Authorities abroad have not been so delicate. In Britain, some of the Palestinians scooped up have tried to protest their detentions. But British judges refused in two separate rulings last week to review their cases, saying the matter is out of their hands because the government is citing national security.

Washington Post correspondent Glenn Frankel reported from London that in both cases, those arrested claimed they were not terrorists and that deporting them back to the Arab world would endanger their lives. In one case, the man is reportedly a Palestinian relative of Abu Nidal himself.

The other case involves Abbas Cheblak, a Palestinian author and academic with a Lebanese passport who is a senior information officer with the Arab League. He has lived in London for 16 years and has two children who are British citizens. He signed a letter condemning the Iraqi invasion of Kuwait, but the British Home Office said he had "known links with an organization" that could take terrorist actions against "unspecified Western targets."

Cheblak's only recourse now is to a Home Office advisory panel of "three wise men," a group that has not met in three years. He remains in custody as "an unacceptable security risk."

Home Secretary Kenneth Baker said Thursday: "There will not be a witch hunt in this country. Let me make that absolutely plain. . . . {But} I have to take action when I have advice in the interests of national security, and that I am doing."

The Home Office said many of the Iraqi nationals in Britain as students are believed to be spies whose basic function has been to monitor and harass Britain's large Iraqi community. The 33 "students" recently detained were handed over to the Ministry of Defense as prisoners of war because, officials said, they were believed to be "members of the Iraqi armed forces."

In France, Interior Minister Pierre Joxe last Tuesday decided after meeting with European Community colleagues to put 16 alleged pro-Saddam activists -- Moroccan, Algerian, Lebanese and Iraqi citizens living in France -- on a plane to Yemen. Two other Arab civilians were expelled to Tunisia and Morocco, Washington Post correspondent William Drozdiak reported.

Joxe said the expulsions were an "absolute urgency." He added that "the threat of attacks has to be taken seriously . . . because Iraq has announced its intentions to deploy the terror weapon."

Among those labeled "undesirable" were the Algerian leader of the Islamic Salvation Front in Marseilles and the editor of a leading Iraqi publication in France. French officials said they were more worried about two lesser lights: a Jordanian law student known as chief of the Iraqi Baathist Party cell in Montpelier and an Algerian who belonged to the Palestine Student Committee in Aix-en-Provence. All were given one-way tickets to Yemen.

Cannistraro, now with the National Strategy Information Center here, said the crackdown was more responsible for the lack of "terrorist spectaculars" than was any disruption of communications with Baghdad.

Command and control in the European theater, he said, can always come from Saddam's half-brother, Barzan Ibrahim, a former head of the Iraqi secret police who is now Iraq's permanent representative to the United Nations Conference on Human Rights in Geneva.

The Manila blast, Cannistraro said, shows Saddam is "pulling out all the stops, all the resources he has in his sack. The old rules of plausible deniability are off the books because of the war."

But if Iraqi cells have been disrupted, he said, "the major concern now has to be with {Palestinian} groups like Abu Nidal that don't depend on local support from {Iraqi} embassies and government infrastructures."