Omar Mateen's wife has told US law enforcement officers that she tried to stop her husband from carrying out his bloody attack on an Orlando gay club, it has been reported.

Nour Salman, 30, is said to have been with Mateen when he bought ammunition and a holster as he prepared for the attack that murdered 49 people.

She also drove him out to Pulse, the gay club, so that he could scope it out, Federal Bureau of Investigation sources familiar with the case told the NBC News television channel.