Goncalo Ramos also added a late double to make sure of the points, extending PSG's unbeaten streak and moving it 13 points clear of second-place Marseille on the table.

Dembele, who struck three times in PSG's 4-1 win at Stuttgart in the UEFA Champions League in midweek, opened the scoring for the visitors just before the half-hour mark, tapping into an empty net from Bradley Barcola's short cross.

However, Brest clawed itself back level just five minutes after the break through Romain Del Castillo's strike across goal.

Dembele gave them a two-goal cushion with two goals in five minutes shortly after. He neatly latched onto Khvicha Kvaratskhelia's deflected pass to slot in his second before getting his third from the edge of the six-yard box.

Ludovic Ajorque looked to have set up a nervy ending by pulling one back in the 71st minute, but Ramos's late double put the result beyond doubt as he scored twice from close range in the closing stages.

Defending champion PSG moved to 50 points from 20 matches, while eighth-placed Brest remained on 28 points.