London: WikiLeaks said on Sunday it was under a cyber attack but stressed this would not stop the publication of classified US documents, in a message on Twitter.
"We are currently under a mass distributed denial of service attack," the whistle-blower website said in a statement on its Twitter feed, just hours before an expected mass release of the documents.
But it insisted that the Spanish, French, German, British and US newspapers that were planning to publish the information later Sunday would go ahead, in the face of strong opposition from the United States.
"El Pais, Le Monde, Spiegel, Guardian and NYT (the New York Times) will publish many US embassy cables tonight, even if WikiLeaks goes down," it said.
The WikiLeaks website was not immediately accessible.
Earlier, WikiLeaks chief Julian Assange said the document release would cover "every major issue in every country in the world".