French diplomats conveyed to Ambassador Ali Ahani their "deep concern" over the detention of the 15 who were seized by Iran during what Britain said was a routine patrol of Iraqi waters in the northern Gulf on Friday, said foreign ministry spokesman Denis Simonneau.
"We recalled our solidarity with the British and asked Iranian authorities to release as early as possible the detained sailors," said Simonneau.
"In the meantime, the Iranians must allow them to exercise their visitation rights," he added.
Tehran maintains that the 15 sailors and marines had trespassed into Iranian territorial waters.