Militants from the Nigeria-based Islamic extremist group Boko Haram crossed the border into neighbouring Niger, setting homes ablaze and killing at least 40 people, a local government said Thursday.

The attack marks the latest attempt by Boko Haram to strike inside neighbouring countries that have joined the Nigerian military's attempt to quash the group. Earlier this week, authorities in Chad blamed the group for two suicide bombings in the capital that left at least 33 people dead.

Yakouba Soumana Gaoh, the governor of Niger's Diffa region, said his country's army was hunting down those responsible for the violence overnight in the towns of Lamana and Ngoumawa.

"The attackers looted stores, burned villages and shot at people who tried to flee," he said.

In April, Boko Haram attacked Niger and killed at least 58 people, saying the assault was in retaliation for Niger's support of the Nigerian military.

In another development, Chad's military spokesman Col. Azem Bermandoa confirmed that an aerial assault had been launched Wednesday inside Nigeria on Boko Haram positions. The government also has barred women from wearing burqas in public for fear that suicide bombers could use them to hide explosives.

Boko Haram's six-year-old uprising is blamed for the deaths of an estimated13,000 people. More than 1.5 million have been driven from their homes, some across borders.

Boko Haram took control of a large swath of northeast Nigeria until a multinational force this year forced them out of towns and villages, but the group still engages in cross-border hit-and-run attacks.

On Wednesday, at least 63 people were killed in an explosion in Monguno, Nigeria, when civilian self-defence fighters brought a large sack of home-made bombs discovered at an abandoned Boko Haram camp back to the village.