Canadian authorities have charged a railway company and three employees with criminal negligence following last July's train derailment in Lac-Megantic, Quebec, which killed 47 people.

Montreal, Maine and Atlantic Railway Ltd and employees Thomas Harding, Jean Demaitre, Richard Labrie were charged with 47 counts of criminal negligence causing death.

Spokesman for the public prosecutor's office Rene Verret said Mr Harding was the driver of the train, Mr Labrie was a controller at MM&A, and Mr Demaitre was director of operations.

Mr Verret said the three were placed under arrest yesterday and will appear in court later this afternoon in Lac-Megantic.

The derailment occurred after a single engineer, Mr Harding, parked his train for the night on a main line uphill from the small town.

The train of oil tankers started rolling and eventually derailed, exploding into balls of fire and flattening the centre of the town.

US-based MM&A filed for bankruptcy protection in the wake of the disaster.

MM&A Chairman Edward Burkhardt, who was not charged, said in March he had been in touch with investigators "from time to time" to provide requested information.

The company initially blamed the catastrophe on the failure of the train's pneumatic airbrakes after an engine fire.

Mr Burkhardt later said the train's engineer did not apply an adequate number of handbrakes to hold the train in place.