By David Alexander
WASHINGTON (Reuters) - U.S. officials are worried about what other secret documents the whistle-blowing website WikiLeaks may possess and have tried to contact the group without success to avoid their release, the State Department said on Friday.
The shadowy group publicly released more than 90,000 U.S. Afghan war records spanning a six-year period on Sunday. The group also is thought to be in possession of tens of thousands of U.S. diplomatic cables passed to it by an Army intelligence analyst, media reports have said.
"Do we have concerns about what might be out there? Yes, we do," State Department spokesman P.J. Crowley told a briefing, adding that U.S. authorities have not specifically determined which documents may have been leaked to the organization.
He said the State Department could not confirm the longstanding reports that WikiLeaks is in possession of a large set of U.S. diplomatic cables.
But the fact that the documents released on Sunday contained a handful of State Department cables suggests that other secret diplomatic messages may have been included in data transmitted to WikiLeaks, Crowley said.
"When we provide our analysis of situations in key countries like Afghanistan and Pakistan, we distribute these across the other agencies including to military addresses," Crowley said. "So is the potential there that State Department documents have been compromised? Yes."
Both Crowley and White House spokesman Robert Gibbs urged WikiLeaks and its founder, Julian Assange, not to release further classified government documents.
Gibbs, noting WikiLeaks claims to have at least 15,000 more secret Afghan documents, told NBC's "Today" show there was little the government could do halt the release of the papers.
"We can do nothing but implore the person who has those classified top secret documents not to post anymore," Gibbs said. "I think it's important that no more damage be done to our national security."
'BLOOD ON THEIR HANDS'
Both Crowley and Gibbs expressed concern that the document dump might expose U.S. intelligence-gathering methods and place in jeopardy people who had assisted the United States.
"You have Taliban spokesmen in the region today saying they're combing through those documents to find people that are cooperating with American and international forces. They're looking through those for names. They said they know how to punish those people," Gibbs said.
Assange told the BBC World Service in an interview that Wikileaks had held back the remaining 15,000 papers to protect innocent people from harm, and was reviewing them at the rate of about 1,000 a day. He did not say if and when they would be published.
Assange hit back at comments from Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, on Thursday, that Wikileaks "might already have on their hands the blood of some young soldier or that of an Afghan family."
He accused Defense Secretary Robert Gates of attacking Wikileaks to "distract attention from the daily deaths of civilians and others in Afghanistan."
"There is real blood in Afghanistan, and it has come about as a result of the policies of Mr Gates and the Obama administration and the general conflict in the region," Assange said.
Crowley said the government had tried to make contact with WikiLeaks but had not been successful in establishing a line of communication.
"We have passed messages to them," he said. "I am not aware of any direct dialogue with WikiLeaks."
Assange said Wikileaks had used the New York Times as an intermediary to request White House assistance in vetting the document trove prior to publication, but did not receive a response.
Crowley said: "Intelligence services all over the world will be looking over them and seeing what they can glean in terms of how we gain information."
He added: "Behind these documents is a very important intelligence system that is vital to our national security and we are concerned ... that if WikiLeaks continues on its current path this will do damage to our national security."
Gates and Mullen both said on Thursday the document leak had undermined trust in the United States.
Senator Carl Levin, the chairman of the Senate Armed Services Committee, sent a letter asking Gates for an assessment of how badly the military's sources and methods of gathering intelligence had been hurt.
"I am concerned about the nature and extent of the damage caused by the release of these documents," he wrote in the July 28 letter, which was released by his office on Friday.
The Army investigation into the release of the documents is focusing on Army specialist Bradley Manning, who was already charged this month with leaking information previously published by WikiLeaks, U.S. defense officials say.
Manning, who was moved from a detention facility in Kuwait to one at Quantico Marine Base in Virginia on Thursday ahead of his trial, is charged with leaking a classified video showing a 2007 helicopter attack that killed a dozen people in Iraq, including two Reuters journalists.
Manning has not been named as a suspect in the latest leak and investigators are not ruling out the involvement of multiple individuals.
(Additional reporting by Phil Stewart, Susan Cornwell, Deborah Charles and Mark Trevelyan)