Diplomats here are readying themselves for possible embarrassment after whistleblowing website WikiLeaks released 250,000 United States State Department documents.

The classified documents were released this morning and include 1490 cables between the US Embassy in Wellington and Washington, international media reported.

The State Department had told website founder Julian Assange the release would endanger countless lives, jeopardise American military operations and hurt international co-operation on global security issues.

US ambassadors anticipate embarrassing revelations affecting Washington's relations with its allies and other nations.

Prime Minister John Key said New Zealand diplomats and American ones based here were likely to be involved as there were plenty of diplomatic cables sent between the two capitals.

"Naturally there's communication between Washington and Wellington so (there's) every chance that there'll be something released that causes a little bit of embarrassment."

The documents would be taken out of context, Mr Key said.

"If I went away and taped your conversation around the coffee machine this morning it would probably be different to the one that you might publicly release, that's because just the tone and the way you describe things, that's just human nature," he told TVNZ's Breakfast show.

"From New Zealand's point of view we'll just deal with whatever comes out."

Foreign Affairs Minister Murray McCully had been briefed on the release by the US.

The documents show Saudi donors remain chief financiers of militant groups like al Qaeda and that Chinese government operatives have waged a co-ordinated campaign of computer sabotage targeting the US and its allies, according to a review of the WikiLeaks documents published in the New York Times.

The WikiLeaks documents also show US Defence Secretary Robert Gates believes any military strike on Iran would only delay its pursuit of a nuclear weapon by one to three years.