By Issifou Djibo
DIFFA, Niger, Feb 8 (Reuters) - At least five people were killed when a bomber struck a market in the town of Diffa in southeastern Niger on Sunday, after the army repelled an attack by Nigerian Islamist group Boko Haram on the border settlement.
It was the second attack by Boko Haram in three days on Niger's southern border region, where some 2,500 Chadian troops have gathered ahead of a planned military offensive by regional powers against the Islamist group.
Niger's parliament is due to vote on Monday on a proposal to send its troops into Nigeria to help fight Boko Haram.
Residents in Diffa said fighting was heard between around 6 a.m. and 10 a.m. (0600 to 1000 GMT) in the southern outskirts of the town.
"There was fighting between security forces and elements of Boko Haram who tried to enter the town," said a military source. "Fighting is taking place around the bridge at Doutchi. There are many dead."
Local residents said a young boy carrying explosives blew himself up in Diffa's market. Local radio Anefi, however, said the bomb was thrown by a young man on a motor-bike who escaped.
"We have carried five dead bodies out of the market," said a member of the local emergency services. "There are around 15 wounded, some of them in a serious condition."
Chadian forces already crossed into Nigeria last week to the south of Lake Chad to attack Boko Haram in the town of Gambaru, bordering Cameroon.
On Saturday, the governments of Cameroon, Chad, Niger, Nigeria and Benin agreed to establish an 8,700 strong regional force.
Chad has deployed some 2,500 soldiers to neighboring Cameroon and Niger as part of this effort.
Boko Haram has seized territory in northeastern Nigeria as part of a five-year insurgency to carve out an Islamist state on the territory of Africa's top oil producer and biggest economy. Around 10,000 people were killed last year.
Nigeria's electoral commission on Saturday postponed a presidential election that had been scheduled for next weekend until March 28 due to security concerns over Boko Haram's insurgency. (Additional reporting by Abdoulaye Massalaki in Niamey and Daniel Flynn in Dakar; Writing by Daniel Flynn; Editing by Gareth Jones and Stephen Powell)