A fire during a birthday party at a bar in the northern French city of Rouen has killed at least 13 people and injured six.

The blaze in the Cuba Libre bar began in the basement room around midnight on Saturday, Interior Minister Bernard Cazeneuve said.

More than 50 firefighters were called to the fire in the centre of the city.

Reports suggest candles on a cake may have started the fire. Terrorism has been ruled out.

An inquiry is now under way.

The victims are aged between 18 and 25, the Paris-Normandie news website reports (in French).

They are believed to have been killed by a poisonous gas omitted by a material in the ceiling which caught fire.

Prime Minister Manuel Valls said in a tweet (in French): "Deep sadness with regard to the tragedy which mowed down 13 young lives. Compassion and support for the afflicted families."

The authorities praised firefighters for the speed of their response.

A map showing the French city of Rouen