Al-Qaeda threatened Friday to kill the leader of a pro-government force in southern Yemen, putting a bounty on his head, as it seeks to impose itself on the war-torn country. Al-Qaeda's branch in Yemen, in a statement circulated during main weekly prayers in mosques, vowed to kill Abdellatif al-Sayed, the Abyan provincial commander of the Popular Resistance, an alliance of Sunni Islamists, tribesmen, loyalist soldiers and southern secessionists. Accusing him of having "stabbed the mujahedeen in the back," it placed a bounty of 7 million Yemeni riyals ($32,500) on his head and warned that his accomplices would be regarded as "legitimate targets." Saudi Arabia says it has launched an investigation after aid group Doctors Without Borders (MSF) says its coalition targeting Houthi rebels struck one of its clinics. MSF says a coalition airstrike Wednesday near Taiz in southern Yemen hit its clinic there, wounding nine people. In a statement carried Friday on the state-run Saudi Press Agency, the kingdom said it was investigating and vowed "to publish, with the utmost transparency, the findings." However, its statement also said aid groups need "to conduct pre-emptive coordination" with its military campaign. Doctors Without Borders says it provided the clinic's coordinates several times to the military campaign, but it still was struck. An Oct. 26 coalition airstrike destroyed another small hospital run by MSF in Yemen's northern province of Saada.