China on Monday denied any state involvement in cyberattacks on Google and accused the United States of "double standards" as a row with Washington over Internet freedom intensified.

Beijing fired off its latest salvo after the White House said President Barack Obama was "troubled" by Google's statements it had been attacked by China-based hackers, and demanded official answers.

The US Internet giant has threatened to abandon its Chinese search engine, and perhaps end all operations in the country over the cyberattacks. It has also said it is no longer willing to bow to Chinese government censors.

But China said the hacking charges were without foundation.

The "accusation that the Chinese government participated in (any) cyberattack, either in an explicit or inexplicit way, is groundless and aims to denigrate China," an unnamed spokesman for the Ministry of Industry and Information Technology told state news agency Xinhua.

"China's policy on Internet safety is transparent and consistent," he added, saying the country with the world's largest online community was itself the "biggest victim" of hacking.

The Global Times -- an English-language newspaper run by People's Daily, the ruling Communist Party's mouthpiece -- went further, saying the United States itself was a major source of hack attacks.

"The US is the first country to launch cyber warfare," it said in an editorial.

It said Washington had a "cyber army of 80,000 people equipped with over 2,000 computer viruses," citing a US defence expert, Joel Harker.

"'Do unto others as you would have them do unto you.' The golden rule should apply even online," the paper said -- a point made by Xinhua in an editorial calling the US "hypocritical" for criticising others on hacking.

The Global Times also hit out at what it called "Washington's continuous resort to double standards" and said Western criticism of China's Internet policies came "either out of ignorance of the facts, or a Cold War mentality."

In another interview on Xinhua, a spokesman for China's State Council, or cabinet, said Beijing's efforts to remove harmful content from the Internet were legitimate and should be free from "unjustifiable interference".

The Google row, which erupted almost two weeks ago, has threatened to damage Sino-US ties, which are already dogged by trade and currency issues, US arms sales to Taiwan and climate change.

Some US groups are calling on Washington to challenge at the World Trade Organisation China's so-called "Great Firewall" of web censorship.

Last week, Beijing lashed out at Washington after a speech by US Secretary of State Hillary Clinton on Internet freedom, saying the address was "harmful" to relations.

In her speech, Clinton lamented what she said were Beijing's increasing efforts to control what its 384 million web users can see.

Google has not yet stopped censoring search results on google.cn, but Google chief executive Eric Schmidt said last week it would happen soon.

Google vice-president for the Asia-Pacific, Daniel Alegre, said in an interview with Japan's public broadcaster NHK that the company viewed China as a "very important, very strategic market".

"So we hope to be able to remain committed and grow within the market," he said.

The US State Department said Friday that US and Chinese diplomats had held several meetings to discuss the attacks on Google, which the firm said appeared aimed at cracking the email accounts of Chinese human rights activists.

Susan Stevenson, spokeswoman for the US embassy in Beijing, told AFP some of the meetings had taken place in the Chinese capital but declined to give further details.

Meanwhile, the websites of at least five organisations dealing with Chinese human rights and dissident issues were hacked in recent days, one of the groups said Monday.

Chinese Human Rights Defenders, a network of domestic and overseas China activists, released a statement saying attacks on its website began Saturday afternoon and continued for about 14 hours.

It said others reporting cyberattacks included the human rights-related news and information sites Canyu, Rights and Livelihood Watch, and New Century News, as well as the Independent Chinese Pen, a writer's group.