Image copyright Reuters Image caption The train rolled downhill for seven miles (11km) before derailing at Lac-Megantic

Three workers and a railway line will be charged with criminal negligence in the explosion that levelled a Quebec town last year, authorities have said.

Thomas Harding, Jean Demaitre and Richard Labrie, and the Montreal, Maine and Atlantic Railway will be prosecuted, authorities said.

The 6 July blast occurred when dozens of rail tankers of crude oil came loose and crashed in Lac-Megantic.

The town was destroyed and 47 people were killed in the inferno.

Mr Hardin, the train's engineer, was arrested on Monday, as were Mr Demaitre, manager of train operations, and Mr Labrie, in charge of rail circulation that day. They are scheduled to appear in court in Quebec on Tuesday.

Montreal, Maine and Atlantic Railway is now defunct, after Canada suspended its operating licence in August.

The three men and the company each face 47 counts of criminal negligence causing death, Rene Verret of the Quebec prosecutor's office told the Montreal Gazette newspaper

The train with 72 tankers full of crude oil had been parked uphill from Lac-Megantic and was unattended when it rolled out of control downhill for seven miles (11km) into the town, then derailed.

Several tankers exploded, destroying 40 buildings.

The blasts destroyed a large area of Lac-Megantic and forced some 2,000 residents to flee their homes.

Image copyright AP

The company blamed Mr Hardin for failing to set enough hand brakes to keep the train from rolling.