SANAA - Yemen has launched an air strike on the house and farm of a leading Yemen-based al Qaeda militant, a security official said on Wednesday, but there was no immediate word on casualties.

Ayed al-Shabwani, the owner of the house targeted in the Maarib province east of Sanaa, was one of six al Qaeda militants the government had said died in an air strike last week. Al Qaeda at the time denied any of its members had been killed.

Yemen declared open war on al Qaeda last week as pressure mounted to crack down on the global militant group after its Yemen wing said it was behind an attempt on December 25 to bomb a U.S.-bound passenger plane.

Western powers and neighboring Saudi Arabia worry Yemen could turn into a failed state, and fear al Qaeda could exploit the ensuing chaos to strengthen its foothold in the poorest Arab state and turn it into a launchpad for further attacks.

Yemen is also fighting a northern Shi'ite insurgency and faces separatist sentiment in the south.

Yemen gained a reputation as an al Qaeda haven after the September 11, 2001 attacks in the United States, and came under the spotlight after crackdowns on the group in Pakistan and Afghanistan raised fears Yemen was becoming a training and recruiting center for militants.

(Reporting by Mohamed Sudam, writing by Raissa Kasolowsky, Editing by Cynthia Johnston)