France Defence Minister Alain Juppe travelled on Monday to Niger for talks with officials there after two French hostages died during an attempt to rescue them from suspected Al-Qaeda-linked militants.
Juppe's visit comes two days after the young Frenchmen were found dead in the west African desert state after a failed rescue operation by Niger and French troops.
French anti-terror police have already arrived in Niger to investigate the deaths, officials in Paris said.
One of the dead hostages was an aid worker who had been due to marry a Nigerien woman next week. The other was his best man who had just arrived in Niamey for the ceremony, according to France's Journal du Dimanche.
A Nigerien government spokesman said Sunday that three Nigerien security forces had been killed in the attack on the kidnappers, without elaborating on the circumstances of their deaths.