The US has warned India and other key governments across the world about a new potentially embarrassing release of classified documents by the whistle-blowing website WikiLeaks which may harm the American interests and create tension in its ties with its "friends".

"We have reached out to India to warn them about a possible release of documents," State Department Spokesman P J Crowley told PTI.

"We do not know precisely what WikiLeaks has or what it plans to do. We have made our position clear. These documents should not be released," Crowley said, ahead of the expected release by the website of millions of sensitive diplomatic cables.

It is not known yet what is contained in these documents about India-related issues.

The WikiLeaks has said there would be "seven times" as many secret documents as the 400,000 Iraq war logs it published last month.

On his Twitter account, Crowley said the State Department officials have also contacted leaders in Germany, Saudi Arabia, the UAE, Britain, France and Afghanistan.

Secretary of State Hillary Clinton too reached out to Chinese Foreign Minister Yang Jiechi, as the WikiLeaks, the whistle-blower website, is expected to release some three million classified US cables involving some of its key allies including Australia, Britain, Israel, Russia, Turkey and India.

Admiral Mike Mullen, Chairman of the Joint Chiefs of Staff, urged WikiLeaks to stop "dangerous" leaks.

"I would hope that those who are responsible for this would, at some point in time, think about the responsibility that they have for lives that they're exposing... and stop leaking this information," Admiral Mullen, Chairman of the Joint Chiefs of Staff, told CNN.

"It continues to be extremely dangerous," he said. "We are very mindful of the announcement that WikiLeaks made earlier this week, that there is a release of documents pending at some point in the future."