Chad has ended a months-long mission fighting Boko Haram in neighbouring Nigeria and withdrawn its 1,200-strong force across their common border, an army spokesman told AFP on Saturday."It's our troops who went to aid Nigerian soldiers months ago returning home. They have finished their mission," spokesman Colonel Azem Bermandoa said. "None of our soldiers remains in Nigeria," he added, without specifying whether they might be replaced following Friday's pullout."Those who have come back will return to their sector at Lake Chad," Bermandoa said. However, Chad's general chief of staff General Tahir Erda Tahiro said that if countries in the region which have contributed to a multinational anti-jihadist force were in agreement, more troops will likely be sent in."If the states around Lake Chad agree on a new mission there will surely be another contingent redeployed on the ground," Tahiro said. Boko Haram began the insurrection in Nigeria a decade ago, leading to at least 35,000 deaths with violence spilling over into Chad, Niger and Cameroon.A Boko Haram faction aligned with Islamic State West Africa Province (ISWAP) jihadists is highly active around Lake Chad where the group has training bases on the Niger border and regularly carries out raids on military bases and regional security forces.Last month saw 14 people killed with 13 more listed as missing after an attack on a fishing village in western Chad.Countries in the region have banded together to fight Boko Haram and ISWAP with support from civilian defence committees leading to Chad contributing 1,200 troops.Those troops have now pulled back across the border to be "deployed in the Lake Chad region to strengthen security along the border," a senior local official said.Cameroon says it is battling an upsurge in Boko Haram attacks and, according to an Amnesty International report published last month 275 people, including 225 civilians, were killed there last year.