London, Nov 8 : US Government cyber intelligence experts suspect that Beijing sponsored the Chinese hackers who penetrated the White House computer network on multiple occasions, and obtained e-mails between government officials because of their targeted nature attack.

The Financial Times quoted a senior US official as saying that on each occasion, the cyber attackers accessed the White House computer system for brief periods, allowing them enough time to steal information before US computer experts patched the system.

But they concede that it is extremely difficult to trace the exact source of an attack beyond a server in a particular country.

“We are getting very targeted Chinese attacks so it stretches credulity that these are not directed by government-related organisations,” said the official.

The official said the Chinese cyber attacks had the hallmarks of the “grain of sands” approach taken by Chinese intelligence, which involves obtaining and pouring through lots of often low-level information to find a few nuggets.

Some US defence companies have privately warned about attacks on their systems, which they believe are attempts to learn about future weapons systems, The Financial Times reported.

The National Cyber Investigative Joint Task Force, a new unit established in 2007 to tackle cyber security, detected the attacks on the White House. But the official stressed that the hackers had only accessed the unclassified computer network, not the more secure classified network.

White House press secretary Dana Perino declined to comment. The Chinese Embassy also did not comment, but in the past China has called similar allegations reflective of “Cold-War thinking”.

The US has increased efforts to tackle cyber security, particularly since Chinese hackers believed to be associated with the Peoples’ Liberation Army last year perpetrated a major attack on the Pentagon. (ANI)