A former Army counterintelligence agent said Wednesday he helped point military authorities to a soldier who is under scrutiny in the massive leak of secret war records to a self-described whistleblower website.

Timothy Webster, 30, of Santa Barbara, Calif., said a Sacramento-based computer hacker called him May 26 with a hypothetical question: What would you do if a soldier told you he had leaked classified information?

Webster said the hacker, Adrian Lamo, eventually told him that Pfc. Bradley Manning, an Army intelligence analyst, had claimed he gave the WikiLeaks website secret video of a 2007 U.S. helicopter attack in Baghdad.

Lamo confirmed the account, and said he also told Webster that Manning had confided he was planning to send tens of thousands of classified diplomatic reports to WikiLeaks, which is supported by a network of volunteers.

WikiLeaks posted more than 76,900 classified military and other documents, mostly raw intelligence reports from Afghanistan, on its website July 25.

The documents, which illustrate the frustration of U.S. forces in fighting the protracted insurgency conflict, revived debate over the war's uncertain progress. Meanwhile the White House angrily denounced the leaks, saying they put the lives of Afghan informants and U.S. troops at risk.

"I recognized that it might be a pretty hot issue," Webster said in a telephone interview. "Although I'm a civilian now, I've maintained contact with former associates. I indicated to Adrian I could reach out and notify the appropriate people to handle the issue discreetly."

Webster said he alerted Army counterintelligence agents, who contacted Lamo. Manning was detained in Kuwait May 29, three days after Lamo called Webster.

Lamo said he consulted with several people after Manning confided in him, but that it was Webster who got the investigation rolling.

Manning, 22, a native of Crescent, Okla., is charged with illegally downloading 150,000 classified diplomatic cables and a secret video of a military operation in Iraq, and passing the video and some of the documents along to an unnamed third party.

Government officials suspect he is the source of a helicopter cockpit video WikiLeaks posted in April showing U.S. soldiers gunning down a group of unarmed men in Baghdad. The group is believed to have included a Reuters news photographer and his driver.

The Army is currently investigating whether Manning played a role in the leak of the military intelligence reports from Afghanistan that were posted by WikiLeaks.

In his online chats with Lamo, Manning complained of feeling "smart enough to know what's going on, but helpless to do anything."

Christopher Grey, a spokesman for the Army's Criminal Investigations Division, which is leading the probe, said he couldn't discuss any aspects of the investigation.

WikiLeaks confirmed late Tuesday it will split with Courage to Resist, an Oakland, Calif.-based group, the expected $100,000 cost of hiring a civilian defense attorney to supplement the military lawyers assigned to Manning's case.

Manning's supporters plan to rally Sunday at the Marine Corps base in Quantico, Va., where he is being held pending possible military trial.