A suicide attack by a female bomber killed at least seven people at a market in northeast Nigeria on Thursday, the latest bloodshed in a region where multi-national forces are trying to crush Boko Haram Islamists. 

There was no immediate claim of responsibility for the attack in the town of Biu, Borno state, but it resembled a spate of similar bombings blamed on the Islamists militants. 

Boko Haram on Wednesday launched a pre-dawn raid in Gamboru, northeastern Nigeria, looking to overwhelm Chadian troops who had pushed them out of the border town.

The military in N'Djamena said the militants were repelled but the counter-attack was an indication of the task facing regional forces aiming to crush the rebellion.

Niger's government on Tuesday declared a state of emergency in the Diffa region along the border with Nigeria, which has been attacked repeatedly by Boko Haram in recent days.

"The state of emergency is proclaimed in the Diffa region for a period of 15 days," a statement read on state radio said. The measure will grant increased powers to security forces, including to carry out searches.

The U.N. food agency on Tuesday voiced concern for the 125,000 Nigerian refugees who have fled to southeast Niger, where Boko Haram militants have launched attacks in recent days.

"The World Food Program is particularly concerned by the attacks in the north of Nigeria which are spreading to Niger, forcing thousands of people to flee," WFP spokeswoman Elisabeth Byrs said.

Niger's parliament voted unanimously on Monday to send troops to Nigeria to join a regional fight against Islamist extremist group Boko Haram, lawmakers said.

"The resolution was passed unanimously. All 102 lawmakers present voted favourably," said lawmaker Mohamed Ben Omar. Another member of parliament said the resolution authorises the country to send some 750 troops to Nigeria.

Nigeria's Boko Haram fighters launched a fresh attack in neighboring Niger on Monday, as parliament in Niamey was set to vote on joining a regional force against the Islamists.

The insurgents raided a prison in the southeastern border town of Diffa, which they first attacked on Friday, but were repelled after a heavy exchange of fire, humanitarian sources said.

Nigeria's elections will not be postponed past March 28, National Security Advisor (NSA) Sambo Dasuki told AFP in an interview Monday, saying that Boko Haram fighters who forced the delay would be defeated within the coming six weeks.

"Those dates will not be shifted again," Dasuki said when asked if the polls, which had been initially scheduled for February 14, could be pushed back further.

Nigeria on Monday vowed to crush Boko Haram within six weeks as its leader warned a new regional fighting force "will not achieve anything" and the rebels launched a fresh cross-border attack.

National Security Advisor Sambo Dasuki, who this weekend secured a delay to Nigeria's presidential elections, said "all known Boko Haram camps will be taken out" by the time of the rescheduled vote.

Boko Haram fighters waged twin attacks Sunday in Niger, their latest front in an expanding regional insurgency, claiming at least one life, reportedly that of a child.

An international coalition battling against Islamic militants in Iraq and Syria is beginning to win back territory and deprive the jihadists of key funds, U.S. top diplomat John Kerry said Sunday as he denounced the group's "new level of depravity".

Washington has rallied more than 60 countries in the fight against the Islamic State group, and while Kerry told a global security conference it would be a long battle, he said there were signs the strategy was working.