The White House angrily attacked the release of diplomatic cables by WikiLeaks as a "reckless and dangerous action" that puts lives at risk around the world.

"To be clear - such disclosures put at risk our diplomats, intelligence professionals, and people around the world who come to the United States for assistance in promoting democracy and open government," White House press secretary Robert Gibbs said in a statement.

President Barack Obama "supports responsible, accountable, and open government at home and around the world, but this reckless and dangerous action runs counter to that goal," he said.

"We condemn in the strongest terms the unauthorized disclosure of classified documents and sensitive national security information," he added.

An apparent hacker attack crashed the Wikileaks website Sunday, just as 250,000 leaked US diplomatic despatches were being made public, but news media sites carrying edited versions of the cables remained operational. The www.wikileaks.org domain was brought down by a method known as distributed denial of service (DDoS), in which a huge number of computers repeatedly demand web pages from the server, shutting out ordinary human users and causing the server to jam. There was no indication on Sunday who might have mounted the attack. On the social network Twitter, WikiLeaks announced, 'We are currently under a mass distributed denial of service attack.'

Media which had advance access to the cables offered many of them via their own websites. The publishing consortium included the Der Spiegel of Germany, The New York Times, the London newspaper The Guardian and El Pais of Madrid.