NIAMEY (Reuters) - Three suicide bombers killed six people and wounded 37 late on Monday as they gathered at a mosque in southeastern Niger after breaking the Ramadan fast, the government said.

The attack occurred in the city of Diffa, near Lake Chad and the borders with Nigeria, Chad and Cameroon. The area is a stronghold for the militant group Boko Haram, which is fighting to establish an Islamic state in the region. More than 15,000 people have been killed and millions displaced by the conflict.

Interior Minister Mohamed Bazoum said in a statement on Tuesday that one man and two girls carried out the attack. An army spokesman confirmed the death toll, revising down an earlier estimate that 10 people had been killed.

Boko Haram has gradually split into two factions, one of which has pledged allegiance to Syria-based Islamic State. Troops from Niger and the United States killed 11 militants from the Islamic State affiliate in a firefight last December.

Boko Haram sometimes use female suicide bombers in their campaigns against security forces and civilians, in part because they attract less suspicion.

After a deadly assault on the Nigerien town of Bosso in June 2016 killed 32 soldiers, Chad sent 2,000 troops to help Niger, but they were withdrawn in October last year.