PARIS (Reuters) - French police opened an investigation on Friday after a director at the Restos du Coeur charity said he had been stabbed earlier in the day by a couple shouting "Allahu Akbar," the Paris prosecutor's office said.

The director of the Restos du Coeur soup kitchen in Montreuil, east of Paris, said a man who appeared to be of African origin swung an ax at him and missed, before his female accomplice stabbed him with several blows to the stomach, according to a statement by the prosecutor.

The victim told investigators the assailants attacked him inside the charity's premises and shouted 'God is greatest' in Arabic as they ran away. His injuries were not life threatening, the prosecutor said.

In a sign that French officials for now doubt terrorism as a motive, the investigation is being carried out by a regular prosecutor's office and criminal police rather than dedicated anti-terrorism units.

France has been beset by several high profile attacks claimed by Islamist militants over the 18 months. In June, a Frenchman who pledged allegiance to Islamic State stabbed a police commander to death outside his home and also killed his partner.

The country has been under a state of emergency since Islamic State gunmen and bombers killed 130 people in Paris last November.

(Reporting by Paris newsroom; Editing by Richard Lough and Ingrid Melander)