WASHINGTON (Reuters) - Federal prosecutors are looking for any evidence WikiLeaks founder Julian Assange conspired with a former U.S. Army intelligence analyst suspected of leaking classified government documents, The New York Times reported on Wednesday.

U.S. Justice Department officials were trying to determine whether Assange encouraged or helped Private Bradley Manning extract classified military and State Department files from a government computer system, the newspaper said.

If he did, officials believe Assange could be charged as a conspirator in the leak, not just as a passive recipient of the documents who then published them, the newspaper said, citing people familiar with the case.

A Justice Department spokesman declined to comment on the report.

The Justice Department has been looking into a range of criminal charges, including violations of the 1917 Espionage Act, that could used to prosecute the WikiLeaks case.

Prosecutors were studying an online chat log in which Manning is said to claim he had been directly communicating with Assange while downloading government files, The New York Times reported.

Manning bragged about his exploits to former hacker Adrian Lamo, who then turned him into the authorities, Lamo told Reuters.

Manning has been detained at Quantico Marine Base in Virginia after being charged in July with improperly obtaining a classified video showing a 2007 helicopter attack that killed a dozen people in Iraq, including two Reuters journalists.

Assange has been held in a London jail after being arrested in connection with an unrelated investigation by Swedish authorities into alleged sex crimes in that country.

Some legal experts have said it would be difficult for the Obama administration to prosecute WikiLeaks or Assange, who is an Australian citizen, for espionage. Other parts of U.S. law, however, make it easier to prosecute people for unauthorized disclosure of certain classified information.