Chinese hackers attack computer systems of White House, US presidential candidates

According to the government official, the National Cyber Investigative Joint Task Force had discovered the "intrusion," which was most likely "state-sponsored," on the White House's unclassified computer network and had traced back the attacks to servers based in China.

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

The official said that the hackers managed to penetrate the White House system for brief periods that allowed them to steal information before US government experts patched the system.

"For a short period of time, they successfully breach a wall, and then you rebuild the wall...it is not as if they have continued access. It is constant cat and mouse on this stuff," he said.

The more secure classified network has not been breached, he added.

This is not the first time, China has been blamed for hacking into the servers of the US government.

The US government officials strongly believe that Chinese hackers had successfully penetrated Pentagon networks in 2007 and more recently, they had snooped into Barrack Obama's and John McCain's presidential election campaign networks to steal their policy data - information that might be useful in negotiations with a future administration.

Officials at the FBI, which is investigating the incident, have confirmed that the campaign systems of the presidential candidates were hacked into by a "foreign entity or organization" and not by their political opponents.

"You have a problem way bigger than what you understand," a Federal agent had told Obama's team, which thought that their computer systems had been invaded by a phishing virus - malware designed to steal credit-card numbers.

"You have been compromised, and a serious amount of files have been loaded off your system," the agent said.

According to a Newsweek report, after FBI warned of the security breaches, Obama's camp had hired a private cyber security firm to plug the network leaks.

Technical experts in the Obama camp later speculated that the hackers could be Russian or Chinese.

According to Sami Saydjari, CEO of the Cyber Defense Agency, a company that provides security consulting to governments, it is high time the US government took these cyber attacks seriously as they compromise the nation's security.

"I think we haven't made the proper investments in technology over the past few years," Saydjari said, adding that US may be behind countries such as China or Russia.

Agrees Michael Markulec, COO of Lumeta, a company that provides network security solutions to enterprise and government agencies. According to Markulec, hackings into government systems are not uncommon. "The threat is real, this is not the first time we've seen this and I would argue that in some cases, it's state-sponsored," Markulec said.

Meanwhile, the Chinese government has rubbished the allegations, claiming that it is as much a victim as a perpetrator in this cyber conflict.