Nigeria’s Boko Haram fighters launched a fresh attack in neighboring Niger on Monday, as parliament in Niamey was set to vote on joining a regional force against the extremists.

Nigeria's Boko Haram fighters launched a fresh attack in neighboring Niger on Monday, as parliament in Niamey was set to vote on joining a regional force against the extremists.

The insurgents raided a prison in the southeastern border town of Diffa, which they first attacked on Friday, but were repelled after a heavy exchange of fire, humanitarian sources said.

"The attack failed. The assailants were quite easily pushed back," one source told AFP.

Following the rebuffed Boko Haram assault, witnesses in Diffa said a deadly explosion ripped through a local market just a day after it was struck by a mortar shell that killed one person and injured 20.

"Everything blew up -- I saw bodies everywhere," a local merchant told AFP by telephone Monday, confirming other witness accounts that there were both deaths and injuries in the blast.

The renewed violence came as Niger's parliament was expected on Monday to support a proposal to deploy troops inside Nigeria to help in the battle, along with soldiers from Chad, which has a battle-hardened army, and Cameroon.

No casualty toll was immediately available after the raid by Boko Haram, which has widened a deadly six-year insurgency in Nigeria with attacks in neighboring countries.

A journalist in Diffa said he saw the bodies of Boko Haram fighters in a hearse but was unable to count them.

Some Boko Haram fighters sought to hide out in the town. "The soldiers are looking for them, weapons at the ready. The army has encircled Diffa," the journalist said.

Another journalist said some of the fighters were being held in the prison they attacked.