Police in New York have confirmed that they investigated the activities of the ringleader of the July 7 bomb attacks more than two years before the atrocities in London.
Mohammad Sidique Khan was implicated in a plot to blow up synagogues on America’s East Coast in March 2003 - and US officials who took part in the enquiry insist that British intelligence was aware of the operation.
MI5 have always denied knowing that the Yorkshire-born teaching assistant was a potential danger, although Khan’s name was reportedly placed on a US ‘No Fly’ list in 2003 and he was prevented from visiting New York.
Senior British security officials even claimed that Khan had never been under surveillance from any western intelligence agency before the London attacks.
When a new book by US author, Ron Suskind, serialised in The Times last week, disclosed that the CIA were aware of Khan after he made two trips to America in 2002 to contact local Islamic extremists, British security sources questioned whether US intelligence specialists may have confused two men with the family name of Khan.
Police and FBI agents who worked on this operation emphatically deny that. They have told The Times that their investigation into the threat to bomb a number of synagogues involved the same man who led the 7/7 suicide attacks which killed 52 people.
Paul J Browne, Deputy Commissioner of the New York Police Department said: "We were aware of the plot and took appropriate precautions."
The NYPD confirmed to The Times that that plot involved Mohammad Sidique Khan. Warnings from the NYPD were issued to Jewish groups and synagogues at the time.
Survivors of the London attacks and politicians say the claims made in Mr Suskind’s book, The One Per Cent Doctrine, strengthened the case for a full public inquiry into intelligence lapses before the attack on July 7.
Downing Street says that there is no need for any further investigation into the events leading up to the bombing of three underground trains and a double decker bus.
A Joint Terrorism Task Force based in New York, which included FBI agents, New York detectives and immigration staff, liaised with the CIA in Spring 2003 over Khan’s file.
Dan Coleman, a recently retired FBI agent, who was regarded as the Bureau’s foremost expert on Islamic extremism, described Khan as "a very dangerous character" in his report to Joseph J Billy, the assistant director of the FBI counter terror division.
He said yesterday: "I believe this is the man behind the July 7 bombings, and I was perfectly aware that there was another investigation at the time into another man with the family name Khan, from Britain.
"We took the view this Khan (Mohammad Sidique Khan) was too much of a risk to allow into the US so prevented him from boarding his aircraft at Heathrow."
Officers who took part in this operation told how the CIA gave them only 36 hours notice that Khan was booked on a British Airways flight to JFK airport in New York.
One senior figure involved in the enquiry, who asked not to be named, said: "The CIA made clear to us in conversations about this Khan that their counterparts in British intelligence would regard it as a favour if we dealt with him rather than them.
"I remember saying: ‘Do the British think they are sending an unwanted militant to some African dictatorship to take care of because they haven’t the evidence to deal with him?’. I thought this was appalling behaviour."
He said that from the files he read, no British police force was involved. "This was solely intelligence agency to intelligence agency.
"We were also perturbed that we were only given part of the file compiled by the CIA. It showed this individual had been using a hotmail account to communicate with at least five US-based militants, and more abroad.
"The material comprised mainly intercepts obtained by the National Security Agency since the autumn of 2002. Such material is usually routinely copied to Britain’s equivalent, GCHQ. The only exception would be if the CIA was monitoring a British citizen in the UK and didn’t want MI5 to know what they were up to. This did not appear to be the case in this incident."
The source said that the file referred to reports of Khan making two brief trips to the US in 2002, during which time he gave immigration staff at the airport false details about where he was staying.
The first was the Washington Hotel, in the US capital, and the second a domestic address in Bethesda, Maryland. The street existed but not the house number he gave.
After studying the transcripts of e-mails, the officers said Khan was becoming "more strident in tone about wanting to ‘blow up’ synagogues".
"There was no mention of specific targets in these e-mails, nor of suicide bombings or the method for delivering the devices, but it was clear he wanted to take part."
At the time of the 2003 inquiry the Task Force decided they dare not risk losing Khan, so ordered that he should be stopped at the BA ticket counter and told he could not enter the US.
A source who worked on the Task Force enquiry said: "We recommended this man should be watched further but I don’t know what happened after that. This man did not try to enter the US again, so we regarded it as a British matter and we turned to the many other cases we had on our own doorstep."
He said that this investigation was entirely separate to another US enquiry taking place at the same time on another British militant, Mohammed Jamal Khan.
The FBI said in a statement earlier this week that they believe there could have been a mix up over similar names. Mohammed Jamal Khan was sentenced to 9 years in the UK earlier this year for directing a terrorist organisation, including providing weapons and funds to Lashkar e Taiba, a group fighting Indian control in Kashmir.
He had been visiting the US since the 1990’s and was under surveillance by the FBI, and his calls were also monitored by the NSA.
However, there are differences between the two men. Ajmal Khan was from a different part of the UK, was born in Pakistan, was married with two children, and lived with his elderly parents in Coventry - which differs in all respects to the British-born leader of the homegrown July 7 cell, who was born and brought up in Yorkshire.
Mr Suskind said last night: "My sources are plain. There’s no case of mistaken identity here. Everyone involved knows the difference between the two guys.
"For somebody who is an expert in terrorism to mix these men up is like mixing up Tony Blair and Benny Hill.
"In America the sources are clear. There’s not any doubt about it being Mohammad Sidique Khan in this particular incident discussed in the book."
