WASHINGTON (AP) — The State Department says it is studying the computer hard drives used by an Army intelligence analyst in Iraq, trying to assess the potential damage if allegations are true that the analyst leaked tens of thousands of classified diplomatic documents to a whistle-blower website.

Department spokesman P.J. Crowley said Friday that the Bureau of Diplomatic Security is assisting in the forensic analysis of the data stored on one or more hard drives from computers believed to have been used by Army Spc. Bradley Manning, 22, of Potomac, Md.

Manning, who has not been charged with any crime, is being detained in Kuwait pending an Army criminal investigation of unauthorized leaks of classified information.

"We take this seriously," Crowley said. "Any release of classified material to those who are not entitled to have it is a serious breach of our security and, you know, can cause potential damage to our national security interests."

Former computer hacker Adrian Lamo says that Manning claimed in a series of online chats that he downloaded 260,000 classified or sensitive State Department cables and transmitted them by computer to the website Wikileaks.org.

Crowley said examination of the hard drives, which arrived in Washington on Thursday from Baghdad, should allow officials to verify what documents Manning may have downloaded and whether he sent them to an unauthorized recipient.

In a post on Twitter, Wikileaks has denied that it was provided with 260,000 classified documents, but it has not further clarified the matter.

Wikileaks' chief spokesman, Julian Assange, was expected to appear as part of a panel Friday night an Investigative Reporters and Editors conference in Las Vegas, Nev. But a conference spokesman, Mark Horvit, said Assange told him this weekend he wouldn't be coming for security reasons.

In April, Wikileaks posted a leaked video that shows Apache helicopters gunning down unarmed men in Iraq, including two Reuters journalists.

Lamo has said Manning told him he was the source of the 2007 video, a story first reported by the website of Wired magazine.

Lamo has said he reported Manning to military authorities after Manning confided to him in a series of online chats that he had also leaked the diplomatic cables and other classified material. Lamo has said he feared posting of secret documents could cost lives.

According to a transcript of Lamo's online chats with Manning, published by Wired's website, the intelligence analyst provided one diplomatic cable to Wikileaks as a "test."

That cable — a Jan. 13, 2010, note from the U.S. Embassy in Reykjavik, Iceland, summarizing discussions with Icelandic officials about the country's financial troubles — was posted on Wikileaks.org.

Mark Kimmitt, a retired Army brigadier general and former assistant secretary of state, said in an interview that if the compromised documents include information about U.S. security assistance programs — such as arms sales to friendly governments — they would, if published, "not only be diplomatically embarrassing but would also be a security breach that would have some measure of negative impact."

It would not be the first time sensitive internal government documents have leaked. In November 2006, The New York Times published a secret memo written by Stephen Hadley, then national security adviser to President George W. Bush, questioning whether Iraqi Prime Minister Nouri al-Maliki could be a reliable U.S. partner.

Steven Aftergood, who writes Secrecy News, an e-mail newsletter on government secrecy policies, said if the leaked documents contained only candid assessments, they would not do any damage to national security. But they could still greatly complicate U.S. diplomatic efforts.

"It is a big deal because if the government cannot communicate on a confidential basis, then diplomacy can be crippled," Aftergood said in an interview. "Our foreign interlocutors will be censoring themselves when they speak with us and our own embassies may feel inhibited about what they put in writing."

Aftergood, who has followed government secrecy issues for many years, said that while there have been innumerable isolated cases of leaked secrets, "in terms of voluminous quantities of classified records, there may be no parallel since the Pentagon Papers" case.

He was referring to The New York Times' disclosure in 1971 of a top-secret Pentagon study of the history of U.S. involvement in Vietnam.