Lockheed Martin Corp, the world's biggest aerospace company and the Pentagon's No. 1 supplier by sales, has been hit by an unspecified cyber incident, the government said on Saturday.

The Department of Homeland Security said it and the Defense Department had offered to help gauge the scope of a cyber incident impacting LMCO, as the maker of fighter jets, ships and other major weapons systems is known.

The U.S. government also has offered to help analyze available data in order to provide recommendations to mitigate further risk, Chris Ortman, a Homeland Security official, said in an e-mailed reply to a query from Reuters.

A person with direct knowledge told Reuters on Friday that unknown attackers had broken into sensitive networks of Lockheed Martin and several other U.S. military contractors.

They breached security systems designed to keep out intruders by creating duplicates to SecurID electronic keys from EMC Corp's RSA security division, said the person, who was not authorized to discuss the matter publicly.

(Reporting by Jim Wolf, editing by Will Dunham)