At least 33 people have been killed in central Yemen in fighting in the past two days between Shi'ite Muslim Houthi fighters trying to expand their control and Sunni tribes allied with al-Qaida, residents said on Wednesday.
Residents said tribesmen and allied Ansar al-Sharia militants in the Qifa area, home to powerful Sunni tribes in al-Baydah province, had captured several hilltops, including al-Thaaleb mountain overlooking an al-Qaida stronghold that had been seized by the Houthis.
Yemeni military sources said a U.S. drone had killed seven suspected al-Qaida militants in southern Yemen while they were on their way to carry out an attack.
Yemen, a U.S. ally which shares a long border with the world's top oil exporter, Saudi Arabia, has been engulfed in political turmoil since mass protests ousted its veteran president, Ali Abdullah Saleh, in 2011.
The Houthis, who captured the Yemeni capital Sanaa almost without a fight in September and forced the government to resign, are continuing to expand across the country despite the formation of a new government bringing in supporters of the group and representatives of southern Yemeni separatists.
The Houthis hail mainly from the north.
They have objected to some members of Prime Minister Khaled Bahah's new team, saying they do not meet criteria agreed in a September power-sharing deal.
In the southern Shabwa province, Yemeni military sources said a U.S. drone destroyed a Hilux truck carrying at least seven militants on their way to an attack in the city of Azzan.
Al-Qaida in the Arabian Peninsula often attacks government troops in southern Yemen, which sometimes draws drone strikes. Washington acknowledges using drones in Yemen but does not comment publicly on the practice.