ABUJA, May 18 (Xinhua) -- At least 20 fighters of the Islamic State (IS) were killed in a joint operation by Nigerian and U.S. forces in Nigeria's northeastern Borno State, the Nigerian military said on Monday.

In a statement, military spokesperson Samaila Uba said the operation was carried out in the Metele area of Borno as part of ongoing counter-terrorism efforts in the region.

Uba said the strikes came after the killing of Abu-Bilal al-Minuki, whom the military described as the global second-in-command of IS.

According to the statement, the operation was conducted under a recently established counter-terrorism and intelligence-sharing partnership between Nigeria and the United States aimed at dismantling terrorist networks operating in the region.

The military said the strikes were launched after surveillance detected the gathering and movement of suspected militants, adding that ongoing operations were intended to weaken terrorist networks and deny armed groups safe havens within Nigeria.

The U.S. Africa Command confirmed on Monday that U.S. forces, in coordination with the Nigerian government, conducted additional strikes against IS militants in northeastern Nigeria.

In a statement, the U.S. Africa Command said intelligence had confirmed the targets were IS militants, adding that no U.S. or Nigerian personnel were hurt during the operation, while further assessments were underway.