(Adds comment by U.S. official)

RIYADH, June 13 (Reuters) - Omar Mateen, who killed 49 people in a gun attack at a gay nightclub in Orlando, Florida, travelled to Saudi Arabia in 2011 and 2012, Saudi Interior Ministry security spokesman Major General Mansour Turki said on Monday.

He said Mateen performed the umrah Islamic pilgrimage for 10 days in March 2011, and eight days the following March.

A U.S. official said his travel records indicate that he apparently also visited the United Arab Emirates on one of the trips. Umrah is a lesser pilgrimage to Mecca than the haj, which unlike umrah is mandatory for all Muslims.

However, the official said, the Saudis so far have not provided any evidence that Mateen made contact with known extremists during his visits to the kingdom, adding that anyone thought to be a threat is kept under surveillance by Saudi authorities, although that doesn't mean they have a handle on everyone with radical views or contacts.

Early on Sunday, Mateen stormed the nightclub with a handgun and an AR-15 semi-automatic rifle, fatally shooting 49 people before police killed him in the worst mass shooting in U.S. history. Fifty-three others were wounded, many critically.

U.S. authorities said Mateen called police during the massacre to pledge allegiance to Islamic State, which in recent years declared a caliphate over large swathes of Iraq and Syria. But the depth of his commitment to the militant group is unclear.

(Reporting by Angus McDowall in Riyadh and John Walcott in Washington; Writing by Jon Boyle; Editing by James Dalgleish)