A classified U.S. document obtained by the anti-secrecy group WikiLeaks shows three previously undisclosed participants in the September 11, 2001 plot, The Washington Post reported on Tuesday.

The three Qatari men arrived in the United States on August 15, 2001, conducted surveillance of targets and left the country on the eve of the September 11 attacks, according to the leaked U.S. diplomatic cable.

The three men visited the World Trade Center, the Statue of Liberty, the White House, and various areas in Virginia before flying on to Los Angeles, according to the leaked document.

A U.S. official, speaking on the condition of anonymity, said the three Qataris were looked at within days of the attacks and that investigators concluded they could not be charged, The Washington Post reported.

There is no manhunt, the official was quoted as saying. There is no active case. They were looked at, but it washed out, he was quoted as saying, downplaying a report by Britain's The Daily Telegraph, which said the FBI has launched a manhunt for the previously unknown team of men suspected to be part of the attacks.

The CIA and the FBI declined to comment on the cable, the Post said.

The report said the three Qataris were part of a 2002 FBI list of people whom authorities wanted to interview about the September 11 attacks.

After the men left the East Coast, they stayed at a hotel near the Los Angeles airport. Hotel staff later told investigators the men had pilot-type uniforms and computer printouts listing pilot names, airlines, flight numbers and flight times, the cable said.

The men were scheduled to fly to Washington on September 10, 2001, on the plane that was hijacked the next day and flown into the Pentagon. Instead, they flew to London and then on to Qatar on September 13, according to the report.

The three Qataris were part of a 2002 FBI list of people whom authorities wanted to interview about the September 11 attacks, the Post said .

The leaked cable was sent on February 11, 2010, from the U.S. Embassy in Doha, Qatar to various agencies in Washington, recommending that a man identified as Mohamed al-Mansoori be added to a government watch list, the Post.

He is suspected of aiding people who entered the U.S. before the attacks to conduct surveillance of possible targets and providing other support to the hijackers, the cable said.

Mansoori, from the United Arab Emirates, lived in Long Beach, California in September 2001, the Post said.

(Reporting by JoAnne Allen, editing by Christopher Wilson)

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