Chad and Niger launched a joint army operation against Boko Haram in Nigeria on Sunday, intensifying a regional offensive designed to defeat the Islamic group, military sources said.
It is the first incursion deep into Nigeria by troops from Niger, which have so far only fought Boko Haram in the border area. Chad has already sent troops many kilometres inside northeastern Nigeria and has won territory back from the Sunni jihadist group near the Nigeria-Cameroon border.
"We can confirm that Chadian and Nigerien forces launched an offensive this morning from Niger. The offensive is underway," said Colonel Azem Bermandoa, spokesman for Chad's army.
Niger military sources said troops were attacking militants from the Islamist group in Nigeria's Borno State, having entered via the country's southeastern region near Diffa.
One of the sources said that Abuja had given the green light for the operation. It was not clear how many troops were participating in the offensive.