A huge cargo train has exploded into flames after a collision in the US state of North Dakota.

Two trains – one of which was one-and-a-half kilometres long and carrying crude oil – collided sparking huge flames and a plume of thick black smoke.

Eye witnesses reported hearing two explosions. There are no reports of any injuries but hundreds of residents at the nearby town of Casselton have been evacuated.

A spokeswoman for the emergency services in North Dakota said at least 50 wagons of the train had been uncoupled, but another 56 remained at risk.

The collision reportedly happened near an ethanol plant – a highly volatile and flammable liquid.

It is the latest in a string of incidents which have raised alarm over the rise in crude oil traffic on the railways. According to figures released in North Dakota there was an increase of 67 percent between October 2012 and 2013 in oil transportation by rail.

Earlier this year 47 people were killed when a train carrying oil was derailed in Quebec.