France's prime minister promised Friday there would be no extra military budget cuts after a warning by the defence minister and reports that the heads of the army, navy and air force would quit if there was further belt-tightening.

Manuel Valls's assurances came after Defence Minister Jean-Yves Le Drian wrote a letter to President Francois Hollande saying any more cuts would badly hamper French military operations.

Le Drian's warning comes at a time when France has sent troops to two of its former colonies in Africa, Mali and the Central African Republic, where there has been widespread fighting following coups.

If there are more cuts, "the army will become under-equipped and will not be able to undertake new operations," said Le Drian.

He also wrote that the forces were in a state of "near exasperation" over cuts already announced.

Valls reacted immediately, saying defence spending would suffer no more cuts than have been previously announced.

"It is time to turn the page on ...these rumours," he said. "The military has made a lot of efforts for years and effected a lot of savings."

The French government plans to cut 50 billion euros ($70 billion) from state spending over the next three years, partly through freezing a range of welfare benefits and the pay of most public sector workers.

It also plans to scrap 34,000 defence jobs in six years and do away with some regiments.

The French military employs 285,200 people, of whom around 218,500 are soldiers, sailors and pilots.

The satirical weekly Le Canard Enchaine said the heads of the army, navy and air force met secretly on May 13 and agreed to resign if the military suffered more budget cuts.

They did not issue a statement but leaked their intentions to the press, the weekly said.

There were no details about additional cuts possibly being planned for the military.