The Chadian aircraft pounded Boko Haram positions in the Nigerian border town of Gamboru for a second straight day on Sunday. Two military choppers was used for the targeted bombings in Gamboru that took several hours, with loud explosions that sent thick clouds of smoke into the sky.
The town in far northeastern Nigeria, on the border with Cameroon, was already strafed by two Chadian fighter jets on Saturday, in a raid targeting extremist group Boko Haram, security sources said, as regional efforts to combat the Islamist intensified.
An initial raid was carried out around midday on Saturday by two fighter jets on the town in Nigeria's far northeast along the Cameroon border, sources from Chad and Cameroon said on condition of anonymity.
It was followed by further bombings of areas around the town, Chadian sources said. The raids were aimed at "allowing Chadian soldiers to enter Gamboru," a Cameroon security source told AFP.
It was the same city that the Islamist overran just few months ago in its campaign to seize territory in the region with the intentions of creating Islamic state. The details on damage or casualties were not immediately clear.
"Senior officers from the Cameroon army are located in Fotokol," the Cameroon source said. "The Cameroon and Chadian armies met for the Gamboru operation."
The Cameroon town of Fotokol and its surroundings, just across the border from Gamboru, saw fighting between Chadian soldiers and Boko Haram extremists on Thursday and Friday.
Chad's military said three of its soldiers and 123 militants were killed in the two days of fighting in the area.
Chad has deployed soldiers to Cameroon to help in the fight against the Islamist.
The Boko Haram uprising has become a regional crisis, with the four directly affected countries -- Cameroon, Chad, Niger and Nigeria -- agreeing to boost cooperation to contain the threat.
Nigeria's military said on Thursday that its fighter jets had bombed the northeast town of Malam Fatori, also controlled by Boko Haram.
Witnesses and some media reports said troops and air-force planes from Chad were also involved in that operation on Nigerian soil but Abuja neither confirmed nor denied the claim.
UN Secretary-General Ban Ki-moon on Saturday gave his backing to an African Union proposal to set up a regional five-nation force of 7,500 troops to fight Boko Haram.