Thousands of residents in Nigeria's northeast Adamawa state have fled after troops failed to retake a major town seized by Boko Haram militants.

Residents escaped after Boko Haram repelled a military offensive to retake the town of Madagali, which has been in the hands of the militants since last month.

A local resident, who fled to the town of Mubi 76 kilometres away, says all residents of Madagali, Gulak and Michika have now left their homes.

Defence headquarters declined to comment on the Boko Haram seizure of more towns in the region.