Chad’s army has driven Boko Haram militants out of Malumfatori town in north-eastern Nigeria, a senior official from Niger has told the BBC.
The reported capture of the town, which lies near the borders of Chad and Niger, follows two days of fighting.
Both ground and air forces are reported to have been used in the assault.
Niger officials said Chadian ground forces moved into the town after crossing Lake Chad. It is not known if the operation was approved by Nigeria.