A soldier and an elderly Muslim man were slightly injured when a man drove his car at troops protecting a mosque in Valence in southern France on Friday, officials said.

The driver was seriously wounded when the soldiers shot at him but his injuries are not life-threatening at this stage, the government said in a statement.

The driver was taken to hospital and his motives were not yet known. He had not yet been questioned.

The injured passerby was a 72-year-old worshipper who was hit in the calf by a stray bullet shot by the soldiers, Valence mayor Nicolas Daragon told the iTELE news channel. The soldier had slight injuries to his legs.

"The four soldiers were in front of the mosque, a moderate, quiet mosque, in between two prayer sessions, at a time when many worshippers arrived," Daragon said. "A car drove at them."

The driver tried twice to hit the soldiers and they shot at him on his second attempt, he said.

France has been on high alert since Islamic State militants killed 130 people in shootings and suicide bombings in Paris on November 13. Soldiers are protecting sensitive places across the country, including official buildings and religious sites.