The FBI questioned the accuracy Friday of a new book's claim that U.S. intelligence officials warned Britain that the alleged leader of the July 7 homicide bombings in London had been in touch with extremists plotting to blow up synagogues in the United States.

In his book "One Percent Doctrine," author Ron Suskind wrote that the CIA had warned British intelligence about Mohammad Sidique Khan two years before the Briton led the subway attacks, which killed 56 people including four bombers.

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But the FBI said in a statement that Suskind had apparently confused Mohammad Sidique Khan with Mohammad Ajmal Khan, who is serving a nine-year prison sentence in Britain for supporting terrorism.

But Suskind said in an interview Friday that he stands by his account and that the New York Police Department and his original sources have both confirmed the accuracy of it.

"I have sources very highly placed in the government in this matter and I have gone back to recheck with them," Suskind told AP. "They assure me the account in the book is correct."

Suskind said he knew about both Khans when he wrote the book and added that the statement helps explain how various officials have managed to confuse two investigations.

The FBI noted that the book said Mohammad Sidique Khan, a suspect in the London subway bombings of July 7, 2005 was on the U.S. "No Fly List" and attempted to enter the United States three times. "That reporting is inaccurate," the FBI statement said. "There is an individual named Mohammed Ajmal Khan ... . Many of the facts the book inaccurately associates with Mohammed Sidique Khan do apply to Mohammed Ajmal Khan."

The book — published in Britain on Tuesday after being serialized in The Times of London newspaper — led to calls by the opposition Conservative Party for a new investigation into the terrorist attack, which was carried out by four bombers and was the worst ever in Britain.

"One Percent Doctrine" says that Dan Coleman, who led the FBI's probe of Al Qaeda, had seen files reporting Khan's telephone and e-mail contacts with U.S.-based militants beginning in 2002.

Suskind told the AP on Friday that Coleman also since publicly confirmed the account in the book.

Suskind wrote that Khan was banned from flying to the United States after the CIA discovered in 2003 that he was allegedly planning attacks in U.S. cities.

Suskind's book claims that Khan made at least two trips to the United States in connection with a plot to attack synagogues, and that the CIA shared its information with British intelligence.

E-mails intercepted by the U.S. National Security Agency showed that Khan was in contact with Ahmed Omar Abu Ali, who was sentenced to 30 years in prison in the United States in March after being convicted of plotting to assassinate U.S. President George W. Bush, conspiring to hijack aircraft and providing support to Al Qaeda.