Tracer bullets from a Foreign Legion exercise ignited a huge scrub fire which spread to the outskirts of the city of Marseilles yesterday, destroying a house and forcing the evacuation of hundreds of others.

A non-commissioned officer who allowed the use of the fiery tracer bullets against his standing orders was suspended and faces disciplinary action.

The Prime Minister, François Fillon, who flew to the scene yesterday afternoon, said that there had been a "clear and inexcusable professional blunder".

Download the new Independent Premium app Sharing the full story, not just the headlines

Hundreds of fireman fought to control fires raging across more than 1,300 hectares (3,000 acres) of dry garrigues, or scrub-land, after the tracer bullets were used during a Foreign Legion exercise at Carpiagne, east of Marseilles, on Wednesday afternoon.

At one point, in the early hours of yesterday, it seemed that the fire was going to spread into the eastern outskirts of France's third-largest city. A thousand houses and an old people's home were evacuated. Finally, the efforts of the firemen and fire-fighting planes – and a change in the wind – brought the blaze under control.

One house was destroyed and one fireman was slightly burned, while a dozen others were overcome by fumes.

The French military announced yesterday that an adjutant (sergeant) aged in his 40s had been suspended.

"It appears that tracer munitions were used, strictly against orders," said Colonel Benoît Royal, the head of the army information service.