The Palestine Liberation Organization and a mysterious American were among the outsiders who played a major role in helping to train and equip the professional killers former president Idi Amin used to carry out his reign of terror over the Ugandan nation.

These are some of the embarrassing foreign connections that have been revealed since Amin's "secret" and "confidential" files were spilled onto the streets of Kampala by Tanzanian and Ugandan liberation forces and since individual Ugandans have begun telling of the horrors they witnessed over the past eight years.

A vast array of ideologically diverse foreigners was involved in helping to keep Amin's government afloat. They ranged from the British and Israelis in the early years to the Palestinians, Soviets and East Germans toward the end of Amin's rule.

There is also solid evidence that English, American and Kenyan companies turned a handsome profit by providing Amin with equipment to terrorize his people into submission.

One of Amin's leading foreign allies was the Palestine Liberation Organization, which despite its repeated denials appeared to be deeply involved in training the dreaded State Research Bureau murder squads. It trained and organized bodyguards for Amin and provided advisers who participated directly in the arrest, torture and even the murder of prisoners, according to Ugandans who watched it happen and survived to tell about it.

Another key contributor to Amin's death machine was an American named Frank Terpil, whose Paris-based company supplied a wide variety of explosives, surveillance equipment and weaponry and trained the Bureau's agents in the "art of intelligence sabotage," according to documents obtained here by The Washington Post.

From foot soldier to computer operator, this police state was largely run and armed by foreigners. Amin's 20,000-man army was composed mainly of southern Sudanese mercenaries, Nubian and Rwandan immigrants and the Kakwas and other Moslems from Amin's remote home area on the Sudan and Zaire borders.

In March, several thousand Libyan and several hundred Palestinian troops made a futile attempt to beat back the invading Tanzanian and Ugandan liberation forces. Tanzanian officers say about 200 Palestinians and 400 to 600 Libyans were killed in the fighting.

"It was a foreign occupation army, commented one Catholic priest. "Whenever Ugandans saw their own national Army coming they would run."

Less visible than the soliders were the foreign brains and brawn behind the State Research Bureau. An alleged prime source of "expertise" for its murder squads was the PLO.

According to Apollo Lawoko, a prisoner who escaped the Bureau's clutches, six to 10 Palestinians helped to train raw recruits and "personally took part in the interrogations and killings."

The Palestinians would train the new recruits who were usually Rwandans and Sudanese in tattered or torn clothes," Lawoko said. "Those newcomers were given prisoners to practice on by cutting their throats.

"The old members of staff would stand by with guns. On the first occassion they [the recruits] often balked and attempted to run away. But they would be brought back to finish up the prisoners.

"In these training exercises, the Palestinians were there to give instructions. One famous one was called 'Faizal of the Nile.' He used to boast that he would do everything possible to protect Amin and his government."

Members of the Sembeguya family also cited three instances in which they saw Palestinians taking part in the arrest of civilians.

"In January this year, we were drinking at a club in Kololo when we were rounded up by three Palestinians and four State Research Bureau hooligans," recalled Lydia Sembeguya. "They were led by Hassan, the fat Palestinian from Liberia."

"I've seen Hassan on two occasions actually picking up people and putting them in a boot [trunk] of a car," said her brother, Hudson.

As recently as March, PLO officials denied at a press conference in Dares Salaam, Tanzania, that the Palestinians in Uganda were serving as bodyguards to Amin or with the Ugandan Army, or were supporting Amin's government in any way.

"The PLO assures the world that no Palestinians are fighting alongside Ugandan forces," a PLO spokesman said then.

He acknowledged, however, that the PLO had a "training mission" in Uganda, which was the major Arab presence in that country. Moreover, Tanzanian Army officers reported finding identification papers on Palestinians killed in the fighting tying them to the PLO.

The State Research Bureau was the brain center of the operations with its sophisticated electronic equipment such as computers, radio communications gear and a phone tapping system, all of which appeared to have been supplied by Western companies.

One of the chief Bureau suppliers was Intercontinental Technology, a Paris-based firm whose director, Terpil, is an American who openly boasted here that he used to work for the U.S. Central Intelligence Agency.

[Sources in Washington indicated that he has not worked for the CIA for more than eight years. The CIA declined to comment on any connection it ever had with Terpil.]

According to a contract stamped "secret" found in the State Research Bureau files, Terpil's company sold the Bureau $3.2 million worth of equipment in August 1977. This included disguised antennas, attache cases fitted with tape recorders, explosives, remote radio detonators, a 56-track telephone monitoring system, photographic surveillance equipment and all kinds of interrogation devices.

The contract, the original of which The Washington Post has obtained, also included the "training of selected students in the art and tradecraft of intelligence, sabotage, espionage, etc." and promised they "will become fully trained, versed and confident in the implementation, use and configuration of various explosive devices utilized in general psychological warfare practices."

The Paris address of Intercontinental Technology was a hotel that Terpil apparently used as a blind. He could not be reached for comment.

In Uganda, he described himself as a "consultant" and listed his Kampala address as "The President's Office." His bills are known to have been paid by the State Research Bureau.

[Terpil has been under active investigation by U.S. government authorities for his munitions dealings in a number of countries, including Libya, sources in Washington reported.]

[He is known to have sold explosive devices - including bombs disguised as gifts - to the Libyan government of Col. Muammar Qaddafi, the major defender of the Amin government.]

Terpil was probably not the only American involved with the Bureau.Various Ugandans reported that at least four other Americans, including one black, were seen repeatedly in the company of Bureau officials last year.

Several American companies were also reported to have provided specialized hardware to the Bureau while Harris Corp. put up a satellite for external communications in Amin's home are of Arua.

But British firms were the biggest suppliers of communications equipment to Uganda. Many of the Bureau's electronic experts reportedly went to Britain for special training provided by a Cambridge firm while other British and French firms sold electronic military equipment and military hardware, according to British sources here.

With apparent ideological indifference, Amin also called on Communist advices. The East Germans, who are also involved in security work in Angola, Ethopia and Mozambique, sent advisers to Uganda to train Bureau personnel in telecommunications, electronic and computer operations. They also provided some specialized small arms to the Bureau.

According to a Western diplomat, "The East Germans definitely had people at State Research between 1975 and 1977. But I'm not sure about 1978 when Amin's relations with the Russians soured."

A Ugandan source contended, however, that two East Germans were working in the Bureau "until the very end" and that State Research employes had been sent both to East Germany and the Soviet Union for training.

In addition to bolstering Amin's state security apparatus, Eastern Bloc countries, primarily the Soviet Union, provided the bulk weapons for his armed forces. Amin's jet fighters, tanks and armed cars were almost all Soviet. But in the last year of his rule, Moscow cooled noticeably toward Amin and stopped selling him arms even for cash.

It seems Yugoslavia also may have sold some small arms to Amin. The Yugoslav Embassy here denied it but several Ugandans reported seeing Ugandan Boeing 707 transport planes ferrying arms from Yugoslavia in the fall of 1977.

Besides his foreign supporters, there was a cast of shadowy non-Ugandan characters who maneuvered their way into positions of power in Amin's government. Two of the most in-famous were Bob Astles, Amin's British-born security adviser, and Farook Malik, a Zanzibari of Pakistani origin who helped run the Ministry of Information.

Like Amin, these two were self-confident, aggressive, manipulative, deceptive and above all ruthless.

Astles, who called himself Amin's "odd job man," allegedly was one of the architects of the State Research Bureau and head of the "Anticorruption Squad," a strong-arm organization used to stamp out private enterprise and coffee-smuggling in order to consolidate the lucrative racket in the hands of a few government officials.

According to various accounts, Astles was intimately involved not only in corruption, kickbacks and crooked deals but also in arresting, torturing and killing people. One civil servant said, "Astles even killed people. I have evidence of people arrested by Astles and they never appeared again."

An ex-prisoner related that Astles frequented the State Research Bureau where he "helped draft false confession statements and watched us being tortured into signing them."

The New Ugandan government is currently seeking to have Astles extradited from Kenya on murder and other criminal charges. He fled there shortly before the liberation forces entered Kampala.

Like Astles, Malik also performed numerous tasks for Amin. A State Research Bureau agent who wielded considerable power and oversaw the several dozen Bureau spies within the Information Ministry, he also negotiated the Harris Corp. contract for the Arua satellite station, with, according to several sources, considerable personal profit.

He was, in addition, responsible for reporting on the activities of local and expatriate Asians within Uganda, according to one knowledgeable diplomat. He singlehandedly recruited about 400 Pakistani experts, many of whom also served as informers for the government, according to the diplomat.

In what must now be a much regretted boast, the Pakistani charge d'affaires once told Amin, "We are your eyes and ears in Uganda." CAPTION: Picture, Amin confers with Bob Astles, who was allegedly involved in torture squads. AP; Map, no caption, By Richard Furno - The Washington Post