Chad said Wednesday it inflicted heavy losses on Nigeria’s Boko Haram, killing “over 200” Islamist militants in a border town that it wrested from the rebels in a ground offensive.

Nine Chadian soldiers were also killed and 21 injured Tuesday in Gamboru as regional forces took the fight against the insurgents on to Nigerian soil for the first time, the Chadian army said.

“This toll is provisional,” the Chadian military said in a statement, adding that troops were still combing the town on Nigeria’s border with Cameroon for lingering rebel elements.

Around 2,000 Chadian troops backed by armoured vehicles poured across the border into Gamboru on Tuesday after the African Union last week backed a regional force to take on the extremists.

The sound of automatic gunfire could be heard Wednesday in the town, which has been abandoned by residents after a barrage of air strikes by Chad in the run-up to its offensive, an AFP journalist reported.

While the operation in Gamboru continued, the town of Fotokol on the other side of the border, in Cameroon, came under fresh attack from the jihadists.

“The guys (Boko Haram) entered this morning. The fighting between them and our soldiers is very intense,” a Cameroonian security source in Fotokol told AFP by telephone.

The Cameroonian troops had managed to repel the attack by mid-morning, after Chadian soldiers crossed back from Nigeria to help defend the town.

In Gamboru, the clashes left scenes of desolation, with bodies lying on the ground, houses destroyed, shops gutted and trucks charred.

“We have routed this band of terrorists,” the commander of the Chadian contingent Ahmat Dari told AFP Tuesday, vowing to “hunt them down everywhere.”

Nigerian defence spokesman Chris Olukolade denied that the presence of foreign troops on Nigerian soil compromised the country’s sovereignty.

“Nigeria’s territorial integrity remains intact,” he said, claiming national forces had “planned and are driving the present onslaught against terrorists from all fronts in Nigeria, not the Chadian forces.”

•Adapted from an AFP report. Photo shows troops on patrol.