The US Air Force has blocked its workforce from visiting 25 media websites that published secret diplomatic documents released by WikiLeaks, a spokesman said Wednesday.

The move meant computers used by Air Force employees could not access newsites, including the New York Times, The Guardian and Der Speigel, that have posted the cables online, Pentagon spokesman Colonel Dave Lapan told AFP.

The Air Force took the action because classified information was posted on those websites, he said.

The decision was taken by the 24th Air Force, which is responsible for cyber warfare and security.

No other branch of the military had taken a similar action, and Lapan said the measure was "neither DoD-directed nor DoD-wide," referring to the Department of Defense.

Some cyber analysts called it a clumsy overreaction and the New York Times said "it is unfortunate that the US Air Force has chosen not to allow its personnel access to information that virtually everyone else in the world can access."

Since WikiLeaks began releasing a stream of classified military and diplomatic files, the Pentagon has announced measures to try to prevent more massive leaks and to better regulate how secret documents are handled.

President Barack Obama's administration has already advised federal employees not to read the secret documents published by WikiLeaks unless they have the necessary security clearance.

WikiLeaks has yet to reveal how it obtained hundreds of thousands of secret US diplomatic cables as well as military intelligence documents, but suspicion has centered on Bradley Manning, a low-ranking soldier in Army intelligence, who has been detained since May.