An attack by three suicide bombers outside a mosque in Niger's southeast killed at least six people and wounded dozens of others, the government said on Tuesday.

The attack, carried out by two women and a man, occurred just before midnight on Monday in a southern neighborhood of Diffa, said a statement by the ministry of state. Earlier, a local official had said all three attackers were women.

The suicide bombers tried to enter the mosque during Ramazan prayers, said Elhadji Koura Boukar, a local councilor. The attackers were suspected Boko Haram extremists who had crossed into the country from Nigeria.

Residents in the area about 7 kilometres (4 miles) from the border alerted police. The attackers then detonated their explosives outside the mosque, Boukar said.

The death toll could rise given the serious injuries caused by the blast, he said.

The ministry of state said at least 37 people were wounded, including eight in serious condition.

The Nigeria-based Boko Haram has launched a number of attacks over the years in Diffa.

Niger contributes to the multinational force set up to fight Boko Haram in the region.