More than 1500 Pentagon computers have been taken offline after a hacking attack.

A spokesperson for the US defence department said the system is likely to recover soon and be back online following the attack on Wednesday.

“We obviously have redundant systems in place,” said defence secretary, Robert Gates. “There will be some administrative disruptions and personal inconveniences.”

Gates said the Pentagon computers were shut down once a “penetration of the system” was detected.

Officials in the US denied that the hacked email accounts contained any sensitive military information and are still investigating the cause.

Gates revealed that the Pentagon is attacked hundreds of times a day. He said this hack had caused minimal damage to the computer systems and department operations would continue to work as normal.