WASHINGTON (Reuters) - Saudi King Abdullah has repeatedly urged the United States to attack Iran’s nuclear program and China directed cyberattacks on the United States, according to a vast cache of diplomatic cables released on Sunday in an embarrassing leak that undermines U.S. diplomacy.

The more than 250,000 documents, given to five media groups by the whistle-blowing website WikiLeaks, provide candid and at times critical views of foreign leaders as well as sensitive information on terrorism and nuclear proliferation filed by U.S. diplomats, according to The New York Times.

The White House condemned the release by WikiLeaks and said the disclosures may endanger U.S. informants abroad. WikiLeaks said its website was under attack and none of the underlying cables was visible there Sunday night, though some were posted by news organizations.

Among the revelations in Britain’s Guardian newspaper, which also received an advance look at the documents along with France’s Le Monde, Germany’s Der Spiegel and Spain’s El Pais, King Abdullah is reported to have “frequently exhorted the U.S. to attack Iran to put an end to its nuclear weapons program.”

“Cut off the head of the snake,” the Saudi ambassador to Washington, Adel al-Jubeir, quotes the king as saying during a meeting with General David Petraeus in April 2008.

The leaked documents, the majority of which are from 2007 or later, also disclose U.S. allegations that China’s Politburo directed an intrusion into Google’s computer systems, part of a broader coordinated campaign of computer sabotage carried out by Chinese government operatives, private security experts and Internet outlaws, the Times reported.

MEDVEDEV “PLAYS ROBIN TO PUTIN’S BATMAN”

As described by German news weekly Der Spiegel, the cables contain tart comments such as a U.S. diplomat’s description of German Chancellor Angela Merkel as someone who “avoids risk and is seldom creative.”

Another document described by The New York Times cites a U.S. embassy cable raising the possibility that Libyan leader Muammar Gaddafi may have had a romantic relationship with his Ukranian nurse, who is described as a “voluptuous blonde.”

The newspaper said many of the cables name diplomats’ confidential sources, from foreign lawmakers and military officers to human rights activists and journalists, often with a warning: “Please protect” or “Strictly protect.”

Comments such a description of Russian President Dmitry Medvedev, Russia’s head of state, as playing “Robin to (Prime Minister Vladimir) Putin’s Batman,” are sure to embarrass the Obama administration and to complicate its diplomacy.

The White House said the release of the documents could endanger the lives of people who live under “oppressive regimes” and “deeply impact” the foreign policy interests of the United States, its allies and partners around the world.

“To be clear -- such disclosures put at risk our diplomats, intelligence professionals, and people around the world who come to the United States for assistance in promoting democracy and open government,” White House spokesman Robert Gibbs said.

President Obama is welcomed to the Kingdom of Saudi Arabia by King Abdullah at King Khalid International Airport in Riyadh, June 3, 2009. REUTERS/Larry Downing

“By releasing stolen and classified documents, WikiLeaks has put at risk not only the cause of human rights but also the lives and work of these individuals,” he said.

“DEVASTATING”

Security analysts tended to agree that the release of the documents was a severe blow to U.S. diplomacy, undermining the confidentiality that is vital for foreign leaders and activists to talk candidly to U.S. officials.

“This is pretty devastating,” Roger Cressey, a partner at Goodharbor Consulting and a former U.S. cyber security and counter-terrorism official, said in an e-mailed comment.

The U.S. government, which was informed in advance of the leaked cables’ contents, contacted governments including Russia, and in Europe and the Middle East, to try to limit damage.

The White House also warned readers that the field reporting in the documents is often incomplete and does not necessarily reflect, or even shape, U.S. policy decisions.

Emile Hokayem, a senior fellow at the International Institute for Strategic Studies, said the dramatic revelation that Saudi King Abdullah counseled a U.S. strike on Iran may have been exaggerated for diplomatic effect.

“It’s very possible that the Gulf states have in private adopted very aggressive rhetoric just to stress the urgency of the issue,” Hokayem said. “But I personally doubt that there is an appetite for war as such.”

Among the disclosures reported by The New York Times were:

-- suspicions Iran has obtained sophisticated missiles from North Korea capable of hitting western Europe, and the United States is concerned Iran is using those rockets as “building blocks” to build longer-range missiles;

-- allegations that Chinese operatives have broken into American government computers and those of Western allies, the Dalai Lama and American businesses since 2002;

-- talks between U.S. and South Korean officials about the prospects for a unified Korea should the North’s economic troubles and a political transition lead the state to implode;

-- the South Koreans considered commercial inducements to China to “help salve” Chinese concerns about living with a reunified Korea that is in a “benign alliance” with Washington, according to the American ambassador to Seoul;

-- reporting that Saudi donors remain chief financiers of Sunni militant groups like al Qaeda, and the tiny Persian Gulf state of Qatar, a generous host to the American military for years, was the “worst in the region” in counterterrorism efforts, according to a State Department cable last December;

-- Since 2007, the United States has mounted a secret and so far unsuccessful effort to remove highly enriched uranium from a Pakistani research reactor out of fear it could be diverted for use in an illicit nuclear device.