Yemeni security officials say fighting between local affiliates of Al Qaeda and the Islamic State group has flared in the port city of Aden, killing 22 people at a time when government forces are battling both groups.

They said Sunday that 17 of those killed were from Al Qaeda, three were government forces and two were civilians. The officials, neutral in the conflict pitting government forces against Shiite rebels, spoke on condition of anonymity because they weren't authorized to brief reporters.

Fighting broke out Saturday when government forces sought to retake areas held by local affiliates of both Al Qaeda and IS, causing civilians to flee their homes.

Both extremist groups have exploited the chaos of Yemen's 18-month civil war to expand the territory under their control in southern and eastern Yemen.