Manuel Valls
French Prime Minister Manuel VallsGetty

France's prime minister said he is "open" to a temporary ban on foreign financing of mosques, following a series of deadly attacks linked to Islamic State (Isis). Manuel Valls said the ban would be for an indefinite period, but gave no further details of the policy.

"There needs to be a thorough review to form a new relationship with French Islam," he told Le Monde. He added he was "open to the idea that – for a period yet to be determined – there should be no financing from abroad for the construction of mosques."

He also called for imams to be "trained in France, not elsewhere."

It follows the murder of an 84-year-old priest in a church in Normandy by two men who pledged allegiance to Isis, and the recent attack in Nice when an extremist drove a truck into crowds watching a fireworks display, killing 84.

Valls said France was "at war," and said there would be further atrocities. "This war, which does not only concern France, will be long and we will see more attacks," he added.

"But we will win, because France has a strategy to win this war. First we must crush the external enemy."

The Normandy attackers have been identified as Abdel Malik Petitjean, 19, and Adel Kermiche, also 19. Authorities said that Kermiche had been imprisoned after attempting to travel to Syria to join Isis, and was fitted with an electronic tag at the time of the attack.

Valls said the case showed judges needed to take a "different, case-by-case, approach."