The leak of classified documents on the Afghan war could have "severe and dangerous" consequences for U. S. troops, Defense Secretary Robert Gates said on Thursday.

The Washington Post has reported that Gates told reporters at a news conference in Washington the release could have serious diplomatic repercussions for Washington, saying it "may well damage our relationships and reputation in that key part of the world."

He said, "We have considerable repair work to do."

It was also reported that Adm. Mike Mullen, chairman of the U. S. Joint Chiefs of Staff, went further, saying those responsible for the leak "might already have on their hands the blood of some young soldier or that of an Afghan family."

U. S. officials have said that the Defense Department is reviewing the matter to determine whether any Afghan informants were compromised.

The New York Times reported on Thursday that Pentagon spokesman Col. David Lapan said an assessment team hasn't reached any conclusions, but explained, "In general, the naming of individuals could cause potential problems, both to their physical safety or willingness to continue support to coalition forces or the Afghan government."

Afghan President Hamid Karzai, speaking in Kabul, called disclosure of Afghans who cooperated with NATO and U. S. forces "extremely irresponsible and shocking."

Karzai, after discussing the issue with his advisers, said on Thursday, "Whether those individuals acted legitimately or illegitimately in providing information to the NATO forces, their lives will be in danger now. Therefore we consider that extremely irresponsible and an act that one cannot overlook."

The Times further said that a search through some of the documents released by the group WikiLeaks. org unearthed reports that listed names or identifying features of dozens of Afghan informants, possible defectors and others who were cooperating with coalition forces. (With Inputs from Agencies)