WikiLeaks' next release will be seven times the size of the Iraq war logs, already the biggest leak in US intelligence history, the website said today.

The organisation made the announcement in a brief message posted to its followers on Twitter, giving no information about the content of the coming release or its exact timing - although it did refer to "the coming months" in a separate tweet sent about an hour later.

Although the website has been spilling secrets for years, WikiLeaks shot to international prominence this year with a three leaks. One exposed a classified US helicopter video that appears to show an attack on two Reuters employees and other civilians.

The second made public 77,000 ground-level US intelligence files covering the war in Afghanistan. The third put out 400,000 more such files exposing the daily grind of attacks, detentions and interrogations in Iraq.

Although it isn't clear what WikiLeaks is planning to release next, it allegedly has a huge cache of classified US State Department cables whose publication could give a behind-the-scenes look at American diplomacy around the world.

In the message, the site also said it was under "intense pressure" over the imminent release - a possible reference to WikiLeaks founder Julian Assange's legal problems in Sweden, where he is wanted for alleged sexual misconduct.

It could also be a reference to the constant pressure Assange says is being applied to the website's servers, security, and finances.