Downing Street today condemned the publication of leaked US diplomatic cables thought to feature embarrassing criticism of David Cameron, the Duke of York and the British military.
Washington was at the centre of an international storm after newspapers began publishing details from more than 250,000 secret embassy missives obtained by the WikiLeaks website.
The cables shed light on American dealings with governments around the world and show that Arab leaders have repeatedly urged the US to take military action against Iran.
The spotlight is set to be thrown on UK-US relations over the coming days with further disclosures expected to contain criticism of the Prime Minister and the Duke of York.
UK military operations in Afghanistan are also said to be a target.
The US Ambassador to London, Louis Susman, has personally briefed Downing Street officials about what they can expect to see in the cables.
The Prime Minister's spokesman condemned the publication of the leaks by newspapers, including The Guardian, on the grounds that they could damage British and American national security.
"Clearly we condemn the unauthorised release of classified information," he said.
"The leaks and their publication are damaging to national security in the United States and in Britain, and elsewhere.
"It's important that governments are able to operate on the basis of confidentiality of information."
He added: "It has the potential to be damaging (to national security) but the very fact that this is inhibiting the conduct of governments... governments need to be able to operate on a confidential basis when dealing with this kind of information, and the very fact that it is being leaked is damaging."
Asked whether the Prime Minister was offended by the contents of the cables, the spokesman said: "We are not going to get drawn into the detail of the documents."
The Guardian said it would be publishing details later in the week including allegations of "inappropriate behaviour" by a member of the Royal Family which was said to have "startled" US diplomats.
There was no immediate response from Buckingham Palace to a report in the Daily Mail that the member of the Royal Family involved in allegations of "inappropriate behaviour" was the Duke of York.
The paper said that the Duke - who is a UK trade envoy - had shocked Americans with his "rude behaviour abroad".
The WikiLeaks documents are also said to include "serious political criticism" of David Cameron and "devastating criticism" of British military operations in Afghanistan.
The Guardian said the cables included requests for "specific intelligence" about British MPs.
Sir Christopher Meyer, the former British ambassador to Washington, said the leaks raised questions about keeping government-to-government relations confidential.
"What I can see is more embarrassment than damage - although there is damage - and I'm slightly under-whelmed by the content so far, although the fact and the size of the leak does raise very, very big issues about how you keep things confidential," he told BBC Radio 4's Today programme.
Guardian editor Alan Rusbridger defended his newspaper's publication of leaked information.
"I think it's a good thing that newspapers should bring this stuff into the public arena," he said.
"It's not the job of the media to worry about the embarrassment of world leaders who have been caught saying different things in public or private, especially some of these Gulf states that don't have a free press."
The most striking of the initial disclosures is that Arab leaders have been privately urging the US to take military action to halt Iran's nuclear programme before it is too late.
The King of Bahrain was quoted as telling US diplomats that Tehran's nuclear drive "must be stopped". In another cable, he was said to have warned: "The danger of letting it go on is greater than the danger of stopping it".
He was reported to have been backed by King Abdullah of Saudi Arabia who was said to have repeatedly urged Washington to "cut off the head of the snake" while there was still time.
The cables were said to include a US assessment that Iran has obtained advanced missiles from North Korea that could enable it to strike Western European capitals and Moscow and develop more formidable long-range ballistic missiles.
There were also said to be instructions to US diplomats to spy on the leadership of the United Nations.
They were said to be contained in a series of "human intelligence directives" signed by both the current secretary of state Hillary Clinton and her predecessor Condoleezza Rice.
One directive requested the specification of telecoms and IT systems used by top UN officials and their staff as well as details of "private VIP networks used for official communication, to include upgrades, security measures, passwords, personal encryption keys".
Others instruct diplomats to obtain personal details of people they meet including frequent flyer numbers, credit card details, iris scans, fingerprints, and even DNA material.
The cables were also said to include "harsh" criticism by US embassy staff of their host governments, including Russia and China, and unflattering pen portraits of world leaders.Reuse content