A report by the Financial Times says that email systems of the White House have faced sustained multiple attacks during recent months, which have been tracked back to China.

Earlier in the week, reports revealed that the presidential campaigns of Barack Obama and John McCain were also hacked over the summer.

The Financial Times said that US officials confirmed attacks on the email archives of the White House, a number of times during recent months. The report says that the National Cyber Investigative Joint Task Force, a new unit established in 2007 to address cyber security was the one who detected these attacks and tracked them back to servers based in China.

The report suggests that attackers only managed to break in and access the unclassified White House computer network, but even then, that data could well have some value. The report quoted unnamed sources as saying that cyber attacks might follow the "grain of sands" approach used by Chinese intelligence, which involves parsing through ''low-level information'' to find a few, valuable nuggets.

In the midst of their presidential campaigns, Obama and McCain were also informed that their systems had been hacked, and that some files had been offloaded their system. White House and FBI officials had said that possibly a foreign entity was responsible for the attacks, and had sought information on the evolution of their policy positions, mainly on foreign policy. Thereafter, Obama's campaign had enlisted the services of a computer security firm that plugged the loopholes.

The Financial Times report said that Chinese hackers breached the White House network a number of times, each time stealing some information before the system was patched.

The report suggested that US government cyber intelligence suspects the attacks were sponsored by the Chinese government, on account of their targeted nature.