At least 20 Shiite rebels were killed in clashes with al Qaeda militants and a car bombing in Yemen's central town of Rada, tribal sources said on Monday.
Al Qaeda militants overnight blew up a vehicle parked near a house where the Shiite rebels were gathered in Rada, the sources said, adding that 12 rebels had also been captured in clashes.
Rada was rocked by heavy explosions late on Sunday amid fierce fighting between al Qaeda and the rebels, tribal and security sources said.
"Following the explosions, al Qaeda fighters attacked the rebels, deployed northeast of Rada and along a road" connecting the town in Baida province to neighbouring Dhamar, a Shiite-populated province seized last week by the rebels, a tribal official said.
The rebels, known as Huthis, are seeking to expand their territory across Yemen and have clashed with Sunni tribesmen as well as al Qaeda.
The Huthis have already overrun the capital Sanaa and the Red Sea port city of Hudeida, with almost no resistance, as they seek greater political clout in the country.
They easily captured Dhamar, where they have the support of most of the population, but have met fierce resistance from tribes in Baida and Sunni-majority Ibb.
Yemen has been dogged by political instability since an Arab Spring-inspired uprising forced veteran strongman Ali Abdullah Saleh from power in 2012.
Yemen is located next to oil kingpin Saudi Arabia and important shipping routes in the Gulf of Aden.