Hackers crept into NASA's crucial systems thirteen times in 2011, the American space agency’s Inspector General Paul Martin admitted.

Mr. Martin told Congress that hackers, including China-based, breached the systems’ security and gained access to crucial information, including employees’ accounts at NASA’s Jet Propulsion Laboratory.

In his written testimony to a hearing of the House Science, Space & Technology Committee investigations subcommittee, Martin said, "Some of these intrusions have affected thousands of NASA computers, caused significant disruption to mission operations, and resulted in the theft of export-controlled and otherwise sensitive data, with an estimated cost to NASA of more than $7 million.”

He also admitted that NASA suffered another security failure in March last year, when the agency lost an unencrypted notebook computer that was containing algorithms to command & control the ISS.

Merely 1 per cent of NASA's portable gadgets are encrypted, and the agency suffered a loss of 48 between April 2009 and April 2011.

The space agency reported more than 5,400 incidents of unauthorized access or malware attacks on its computers between October 1, 2010 and September 30 last year.