The White House claims there is no evidence that US government email accounts were hacked.

Google had said yesterday that unknown hackers likely originating from central China had tried to get into the Gmail accounts of hundreds of users.

White House spokesman Jay Carney has said that the administration was taking an 'all government approach' to addressing such intrusions.

Earlier, the US Secretary of State Hillary Clinton said that allegations that hackers sought to access the Gmail accounts of US officials are very serious.

The alleged revelation had come more than a year after Google disclosed a cyber attack on its systems that it said it traced to China, and could further strain an already tense relationship between the Web giant and Beijing.

Google partially pulled out of China, the world's largest internet market by users, last year after a tussle with the government over censorship and a serious hacking episode.