The Nigerian Senate has approved a request by the country's president to extend emergency rule in the restive northeast for another six months.

Lawmakers in Nigeria’s upper house of parliament unanimously voted on Thursday "to extend the state of emergency in Adamawa, Borno and Yobe states on the same terms and conditions."

The Nigerian government originally declared emergency rule in the three states in May in a bid to suppress Boko Haram militants in the region.

Soon thousands of additional troops were deployed into the area, supported by air power.

In a letter to lawmakers on Wednesday, President Goodluck Jonathan claimed that the army had achieved "considerable successes" in containing the militants.

He, however, acknowledged some security challenges still exist and thus emergency rule had to stand for a further six months from November 12.

Jonathan's claims of considerable achievements come despite the continuation of deadly attacks carried out by Boko Haram militants across the northeast in recent months.

Nigerian senators have also called on the army for briefings on the effectiveness of military operations in the area.