In a series of interviews, senior Iraqi intelligence officers who have fled Saddam's regime said that at least one London-based journalist on an Arabic-language newspaper is an agent of the Mukhabarat, Iraq's feared civilian intelligence organisation.

Over the past 10 years, Saddam's agents have recruited Muslims from other countries on pilgrimages to Mecca and paid them substantial sums to travel to the UK, often exploiting illegal people-smuggling networks and the asylum system, to act as informants and agents, they said.

Iraqi intelligence trained, equipped and directed the terrorists who took over the Iranian Embassy in 1980. Saddam's agents have been behind the killing of at least one Iraqi dissident in London and the attempted assassination of several more over the past three decades.

The defectors also revealed that Iraqi intelligence officers had trained Palestinian terrorists at a base near Baghdad and, for the first time, revealed details that confirm Saddam's role in the failed assassination attempt on George Bush senior in Kuwait in 1993. But they denied any link between al-Qaeda and the Iraqi regime.

One of the defectors, a Mukhabarat colonel called Abid Hussein, said: 'Many people were working in Britain to collect information for [the Mukhabarat].' He named a man currently employed as a journalist on an Arabic-language newspaper in the UK as a spy.

A second Mukhabarat defector, Kassm Mohammed al-Hut, said that he knew of the recruitment of four North African Muslims at Mecca in 1994. The men were given rudimentary training and sent to the UK.

Such operations continued throughout the 1990s, he said, with the growing numbers of Iraqis entering the UK illegally to claim asylum providing cover for other agents infiltrated into Britain. Abid, who was interviewed independently of Kassm, confirmed that Mukhabarat officers travelled routinely with pilgrims to Mecca to monitor the behaviour of Iraqi pilgrims and to recruit agents.

Both Kassm and Abid were interviewed in a prison in a city in northern Kurdistan in the presence of Kurdish security officers.

Iraqi operations in the UK date back to the late Seventies, said Abid, who joined the Mukhabarat's foreign intelligence section in 1975 and visited London as a diplomat shortly afterwards.

In 1978, he said, the Mukhabarat was behind the murder of Gen Abdul Razzaq al-Hayef, a former Iraqi Prime Minister, outside a hotel in London. Abid, who fled from Iraq to Germany in 1999 but was imprisoned by the Kurds in the north of the country when he returned for his family, named the two Mukhabarat colonels responsible for the killing.

According to Abid, the Iranian Embassy siege in 1980 was run by a senior Mukhabarat officer called Fawzi al-Naimi. The attackers were recruited from regions within Iraq populated by so-called 'Iranian Arabs' and were trained in the Iraqi capital. 'I was in special operations in Baghdad at the time and I saw their files and their information,' Abid, 49, said.

Weapons for the Iranian Embassy operation were smuggled from Kuwait to London with the help of the Abu Nidal terrorist group, who were close to Saddam's regime at the time, Abid said. In 1982 the Iraqis used Abu Nidal for an attempt to kill the Israeli Ambassador in London. Abu Nidal himself died of multiple gunshot wounds in Baghdad last year.

Throughout the Seventies and Eighties, the London Mukhabarat station at the Iraqi Embassy had three or four officers posted to it. They established a network of informants among journalists, businessmen and Iraqi students. After 1991, the Mukhabarat's activities were restricted. Iraq's diplomatic presence was limited to a special section at the Jordanian Embassy. At least one Mukhabarat officer was able to penetrate the UK, however. He was sent from Baghdad to another Middle Eastern country, where he worked as a journalist.

After building up his cover, he moved to the UK and has been there ever since, Abid claimed. 'There are others but I do not know their identities.'

Espionage operations in the UK are now run from the upmarket al-Mansour district of Baghdad. On the second floor of the middle of five buildings in the complex there are five interlinked rooms known as the 'UK Desk'.

The unit is headed by a former lecturer in English at Baghdad University, who was once the Mukhabarat's head of station in London. General Khalil Ibrahim, the deputy director of the Mukhabarat, is also a former chief of the London station. Reports from agents in the UK are sent to Baghdad through Amman, the defectors revealed