The release of the data comes nearly three weeks after new charges were filed against an American soldier in Iraq who had been arrested on charges of leaking a video of a deadly American helicopter attack in Baghdad in 2007 that killed 12 people, including a reporter and photographer from the news agency Reuters. He was also charged with downloading more than 150,000 highly classified diplomatic cables.

WikiLeaks made public a 38-minute video of the helicopter attack as well as a 17-minute edited version that it called “Collateral Murder.” The abridged version drew criticism for failing to make clear that the attacks happened during clashes in a Baghdad neighborhood and that one of the men fired on by the helicopter was carrying a rocket-propelled grenade.

WikiLeaks has also made public a cable entitled “Reykjavik13,” about the banking crisis in Iceland, which was cited in the criminal charges against the soldier, Pfc. Bradley E. Manning, 22, an Army intelligence analyst. In keeping with its policy to protect the anonymity of its sources, WikiLeaks has not acknowledged receiving the cables or video from Private Manning. In the telephone interview, Mr. Assange, an Australian activist, refused to say whether the war reports came from Private Manning. But Mr. Assange said that WikiLeaks had offered to help pay for Private Manning’s legal counsel or provide lawyers to defend him.

Adrian Lamo, a computer hacker who earlier this year traded instant messages with Private Manning, said the soldier claimed he had leaked the cables and video to WikiLeaks. Mr. Lamo, who in 2004 pleaded guilty to hacking into the internal computer system of The New York Times, said he turned in Private Manning to the authorities for national security reasons. Private Manning, who served with the Second Brigade of the 10th Mountain Division, based at Contingency Operating Station Hammer east of Baghdad, was arrested in May after the military authorities said that he had revealed his activities in online chats with Mr. Lamo.

Investigators now believe that Private Manning exploited a loophole in Defense Department security to copy thousands of files onto compact discs over a six-month period.

WikiLeaks has a core group of about half a dozen full-time volunteers, and there are 800 to 1,000 people whom the group can call on for expertise in areas like encryption, programming and writing news releases.

Mr. Assange, 39, said the site operated from servers in several countries, including Sweden and Belgium, where laws provided more protection for its disclosures.