Nigeria has asked neighboring Niger for support in a week-old offensive against Islamist insurgent bases in its semi-desert frontier region, underlining moves towards West African cooperation against jihadis seen as a cross-border threat.
Concerns grew particularly after Islamist militants associated with al-Qaida seized the north of Mali last year and were dislodged only after French-led military intervention.
Nigeria declared a state of emergency in its northeast states of Borno, Yobe and Adamawa last week before unleashing forces on well-armed and determined Boko Haram militants. Nigeria claimed some early successes on Monday.
Nurudeen Muhammed, Nigeria's minister of state for foreign affairs, delivered the request for help from President Goodluck Jonathan to his Nigerien counterpart Mahamadou Issoufou late on Monday in Niamey.
“We currently have military operations under way in Nigeria in three federal states to combat terrorism and we would like to have Niger's support in the common fight against these terrorists,” Muhammed told Niger state television.
Military sources say Nigerian forces have faced stiff resistance by hardened Islamist rebels entrenched in the north and using cross-border routes to smuggle in weapons.
Nigeria and Niger signed a bilateral defense pact in October 2012 that includes sharing intelligence on Islamist groups and joint military exercises. The deal stipulates that a request for military aid by one nation cannot be refused by the other.
The two West African nations share a porous frontier of more than 1,500 km (940 miles). The fighting in Nigeria has pushed more than a thousand refugees across the border into Niger in the past few weeks, according to U.N. estimates.
Soldiers from Niger and neighboring Chad participated with Nigerian forces in a joint assault on Boko Haram fighters last month in Baga, a fishing settlement on the shores of Lake Chad.
Neighboring countries were alarmed last year when jihadi militants overran vast tracts of Mali's desert north, imposing a violent form of sharia (Islamic law) and establishing training camps, some of which trained Boko Haram operatives.
A lightning French offensive ousted the Islamists from northern Mali's towns but rural pockets of insurgents remain. France is now due to hand over to a U.N. peacekeeping force made up mostly of African troops, the bulk of them Nigerian.
A spokesman for Nigeria's military denied reports that its offensive against Boko Haram would force Abuja to pull some of its 1,200 troops out of Mali.
“The human and material resources of the Armed Forces of Nigeria are being meticulously deployed and quite able to meet its present internal and external assignments,” defense spokesman Brigadier-General Chris Olukolade said in a statement.
“The normal and scheduled rotation of troops in various missions will continue,” he said.
Many analysts say, however, that the intensity of its domestic Islamist threat has forced West Africa's richest and most populous nation to withdraw from its traditional leading role in regional affairs.