MONTREAL (AFP) - Explosions flattened a fireworks factory near Montreal early on Thursday, with noise from the blasts heard and seen from several miles away.

Fireworks could still be seen exploding in the smoke billowing from the warehouse in Coteau-du-lac, Quebec, 50km south-west of Montreal, for several hours after the initial blast at about 1300 GMT (9.30pm Singapore time), according to television images.

The authorities said they will be unable to determine what caused the explosions until it is safe to approach the demolished factory to investigate.

No injuries were reported, but dozens of people were evacuated from nearby homes and a campground as a precaution.

A highway connecting Montreal and Toronto was also closed, as was a train line linking Montreal to Ottawa.