Iraqi secret police believed that the notorious Palestinian assassin Abu Nidal was working for the Americans as well as Egypt and Kuwait when they interrogated him in Baghdad only months before the Anglo-American invasion of Iraq.

Hitherto secret documents which are now in the hands of The Independent – written by Saddam Hussein's brutal security services for Saddam's eyes only – state that he had been "colluding" with the Americans and, with the help of the Egyptians and Kuwaitis, was trying to find evidence linking Saddam and al-Qa'ida.

President George Bush was to use claims of a relationship with al-Qa'ida as one of the reasons for his 2003 invasion, along with Iraq's possession of weapons of mass destruction. Western reports were to dismiss Iraq's claim that Abu Nidal committed suicide in August 2002, suggesting that Saddam's own security services murdered him when his presence became an embarrassment for them. The secret papers from Iraq suggest that he did indeed kill himself after confessing to the "treacherous crime of spying against this righteous country".

The final hours of Abu Nidal, the mercenary whose assassinations and murderous attacks in 20 countries over more than a quarter of a century killed or wounded more than 900 civilians, are revealed in the set of intelligence reports drawn up for Saddam's "presidency intelligence office" in September of 2002. The documents state that Egyptian and Kuwaiti intelligence officers had asked Abu Nidal, whose real name was Khalil al-Banna, to spy for them "with the knowledge of their American counterparts".

Five days after his death, Iraq's head of intelligence, Taher Jalil Habbush, told a press conference in Baghdad that Abu Nidal had committed suicide after Iraqi agents arrived at the apartment where he was hiding in the city, but the secret reports make it clear that the notorious Palestinian had undergone a long series of interrogations prior to his violent demise. The records of these sessions were never intended to be made public and were written by Iraqi "Special Intelligence Unit M4" for Saddam. While Abu Nidal may have lied to his interrogators – torture is not mentioned in the reports – the documents appear to be a frank internal account of what the Iraqis believed his mission in Iraq to be. The papers name a Kuwaiti major, a member of the ruling Kuwaiti al-Sabbah family, as his "handler" and state that he was also tasked to "perform terrorist acts inside and outside Iraq". His presence in the country "would provide the Americans with the pretext that Iraq was harbouring terrorist organisations," the reports say.

"Coded messages indicate that the Kuwaitis asked him indirectly to find out whether al-Qa'ida elements were present in Iraq. Our conclusions were confirmed when he [Abu Nidal] started to mitigate his actions with irrational answers when asked about the data against him. He attempted to sidetrack his answers by not being specific and referring to historical matters. It was noted by the investigators that he went from short, ambiguous and unclear replies to generalities ... he seemed perturbed ... But once he became convinced of the weight of the evidence against him concerning his collusion with both the American and Kuwaiti intelligence apparatuses in co-ordination with Egyptian intelligence, he realised that his treacherous crime of spying against this righteous country had been exposed ..."

Abu Nidal was no stranger to Iraq. He had operated from Baghdad, Damascus and the Libyan capital of Tripoli when the regimes wanted to use him as a "gun for hire". It was Iraq which paid him to organise the attack on the Israeli ambassador to London, Shlomo Argov, in 1982, an attempted assassination which prompted Israel to accuse Yasser Arafat of responsibility and to begin its disastrous invasion of Lebanon, and Colonel Muammur Gaddafi later established a close relationship with Abu Nidal. In 1985, his crazed gunmen attacked Israeli-bound passengers at Rome and Vienna airports, killing a total of 18 people. His biographer Patrick Seale, who suggests that for some time Abu Nidal even worked for Israel's Mossad intelligence agency, has written of how, when he feared treachery in his own ranks, a suspected spy would be buried alive, fed through a tube for days and then – if Abu Nidal's "court" deemed death appropriate – a bullet would be fired down the tube.

His own interrogation at the hands of Saddam's secret police, will therefore appear equally appropriate punishment for so cruel a man. Among the other crimes of which he was accused in the Iraqi intelligence report was the preparation of 14 booby-trapped suitcase bombs to be used on foreigners – Swiss and Austrian, according to the intelligence file – in the northern Kurdish area of Iraq, at the time a US-supported "safe haven", and an attempt to recruit new members for his so-called Fatah Revolutionary Council among Palestinians wounded by the Israelis in the West Bank and Gaza who were recovering in Baghdad hospitals.

There are some oddities in the report and some unanswered questions. It says, for example, that Abu Nidal originally infiltrated Iraq from Iran on a false Yemeni passport years earlier, but that this was facilitated by his own representative in Kuwait, named as Nabil Uthman. Abu Nidal was said to have communicated to Kuwait via coded messages sent through Lebanon and Dubai. The papers give his date of birth as 1939 – he is believed to have been born in Jaffa in what was then Palestine in 1937 – and state that he resided in Libya in 1984 but "had no links with the Libyan authorities". He is also stated to have been imprisoned by the Egyptian security services for two months. The man who is said to have provided Abu Nidal with a "safe house" in Baghdad was interrogated in 2002 alongside the Palestinian and is named as Abdulkareem Mohammed Mustapha.

Could Abu Nidal really have entered Iraq from Iran, whose own intelligence services, would surely have questioned him? Could Abu Nidal have lived in secret in the Baathist state of Iraq without Saddam's own mukhabarat finding him? And for how long was he interrogated? The documents give us no answers to these questions.

His end is, however, recorded bleakly. "Upon being asked to accompany those charged with guarding him to a more secure location to continue the interrogation procedures, he requested that he be allowed to change his clothes. On entering his bedroom, he committed suicide. Unsuccessful attempts were made to resuscitate him ..." Nothing is known of the fate of Abdulkareem Mustapha, only that he was "submitted to court". But we do know where Abu Nidal now lies.

"The corpse of Sabri al-Banna", the final report concludes, "was buried on 29/8/2002 in al-Karakh's Islamic cemetery [in Baghdad]. Until a final resting place is found, a marker designates the place of burial and it was documented on video as well as on still photographs as 'M7'." No "final resting place" for this savage man appears ever to have been found.

Years of terror A man as feared as Bin Laden

Abu Nidal, left, was once as feared as Osama bin Laden. His most notorious attacks included:

*1978 His "Black June" movement blamed for murdering PLO members in London, Paris, Madrid, Brussels, Kuwait and Rome.

*1982 Israeli ambassador to Britain, Shlomo Argov, shot in Mayfair, leaving him permanently paralysed.

*1984 Jordanian airliner attacked by rocket on take-off from Athens. Assassinations included the British cultural attaché in Athens and the British deputy high commissioner in Mumbai.

*1985 Egyptian airliner hijacked – six passengers murdered and 60 killed when the plane is stormed by Egyptian commandos.

*1985 Gunmen massacre 18 and wound 120 in attacks on El Al ticket desks at Vienna and Romeairports, bottom left.

*1986 Machine-gun attack kills 22 in a synagogue inIstanbul; at least 20 passengers and crew are killed when Pan Am jet hijacked in Karachi, bottom right.

*1988 Nine killed and 98 wounded when gunmenattack the Greek cruise ship the City of Poros.

Belfast Telegraph