BEIJING — Contacts told American diplomats that hacking attacks against Google were ordered by China’s top ruling body and a senior leader demanded action after finding search results that were critical of him, leaked U.S. government memos show.

One memo sent by the U.S. Embassy in Beijing to Washington said a "well-placed contact" told diplomats the Chinese government coordinated the attacks late last year on Google Inc. under the direction of the Politburo Standing Committee, the apex of Communist Party power.

The details of the memos, known in diplomatic parlance as cables, could not be verified. Chinese government departments either refused to comment or could not be reached. If true, the cables show the political pressures that were facing Google when it decided to close its China-based search engine in March.

The cable about the hacking attacks against Google, which was classified as secret by Deputy Chief of Mission Robert Goldberg, was released by WikiLeaks.

The New York Times said the cable, dated early this year, quoted the contact as saying that propaganda chief Li Changchun, the fifth-ranked official in the country, and top security official Zhou Yongkang oversaw the hacking of Google. Both men are members of the Politburo Standing Committee.

The cable notes that it is unclear if Chinese President Hu Jintao and Premier Wen Jiabao were aware of the reported actions before Google went public about the attacks in January.

The Times, however, said doubts about the allegation have arisen after the newspaper interviewed the person cited in the cable, who denied knowing who directed the hacking attacks on Google. The Times did not identify the person it interviewed.

Another contact cited in that cable said he believed an official on the top political body was "working actively with Chinese Internet search engine Baidu against Google’s interests in China."

Google’s relations with Beijing have been tense since the U.S.-based search giant said in January it no longer wanted to cooperate with Chinese Web censorship following computer hacking attacks on Google’s computer code and efforts to break into the e-mail accounts of human rights activists. Google closed its mainland China-based search engine on March 22 and began routing users to its uncensored Hong Kong site.

Google’s spokeswoman in Tokyo, Jessica Powell, said the company had no comment on the cables released by Wikileaks, and on the hacking attacks, referred to a January statement that said it had evidence that the attack came from China. Google at the time declined to say whether the government was involved.

A man who answered the phone at the spokesman’s office of the Ministry of Industry and Information Technology said no one was available to comment Sunday. Calls to the Foreign Ministry and the State Council Information Office, which is responsible for regulating Internet contact, rang unanswered.

The hacking that angered Google and hit dozens of other businesses was part of a rash of attacks aimed at a wide array of targets, from a British military contractor to banks. Experts said then the highly skilled attacks suggested the military or other government agencies might be breaking into computers to steal technology and trade secrets to help state companies.

In February, Peng Bo, a high-ranking official with the Internet bureau of the State Council Information Office, said the Chinese government was not involved in or supportive of cyber attacks, and called such accusations "sheer nonsense."

A separate cable released by WikiLeaks showed a Politburo member demanded action against Google after looking for his own name on the search engine and finding criticism of him.

In the version of the May 18, 2009, cable released by Wikileaks, the identity of the official was apparently removed. But the Times reported it was Li, the propaganda chief.

The cable, classified as confidential, cited a source as saying the Chinese official had realized that Google’s worldwide site is uncensored, capable of Chinese language searches and search results, and that there is a link from the home page of its China site, google.cn, to google.com.

The official "allegedly entered his own name and found results critical of him," and asked three government ministries to write a report about Google and "demand that the company ceases its ‘illegal activities,’ which include linking to google.com," the cable said.

The cable said American officials could neither confirm nor deny the details given by the contacts about the Chinese leadership’s action.

A contact also said that China asked its three state-owned telecommunications companies to stop working with the search giant, the cable showed. China’s main state-owned phone carriers are China Mobile, China Unicom and China Telecom.