Police in Quebec are assuming that all those missing after Saturday’s deadly train accident in the town of Lac-Megantic are dead.

Spokesman Michel Forget also reduced the total number of dead and missing to 50 from 60.

He said 20 bodies have been recovered.

Meanwhile, attention focused on the CEO of the railway's parent company, who faced jeers from local residents.

Edward Burkhardt blamed the engineer for failing to set the brakes properly before the unmanned Montreal, Maine & Atlantic Railway train hurtled down an 11km incline, derailed and ignited in the centre of Lac-Megantic.

Mr Burkhardt said the train's engineer had been suspended without pay and was under "police control".

All but one of its 73 cars was carrying oil, and at least five exploded.

The crash has raised questions about the rapidly growing use of rail to transport oil in North America, especially in the booming North Dakota oil fields and Alberta oil sands far from the sea.

The intensity of the explosions and fire made parts of the devastated town too hot and dangerous to enter and find bodies days after the disaster.

Only one body has been formally identified, said Genevieve Guilbault of the coroner's office.

She described efforts to identify the other remains as "very long and arduous work".

The derailment is Canada's worst railway disaster since a train plunged into a Quebec river in 1864, killing 99.