14 people have been killed and four injured after a bus collided with a truck and burst into flames east of Moscow.

Rescue workers were forced to remove the roof from the twisted metal frame of the bus on the outskirts of Petushki, a small town around 100km east of Moscow.

Local media reported that most of the victims were traders travelling to a Moscow market from the city of Ulyanovsk.

Emergency Ministry spokeswoman Lyudmila Martynova stressed that the number of dead and injured could change due to the difficulty of identifying remains from the burned-out bus.

Local news reports earlier said 25 people had died in the accident.

There were differing reports about the cause of the accident, with some officials saying one of the truck's tyres had blown out, while the head of the local traffic police said the truck driver had fallen asleep at the wheel.