At least 12 people were killed in fierce overnight clashes between army-backed Yemeni tribes and Shia Huthi rebels pressing a protest campaign against the government.
Fighting raged in Jawf province north of Sanaa as rebels sought to seize routes to the capital where their supporters have staged weeks of escalating protests against the central government.
Tribal sources said fighting in the Ghayl and Majzar regions straddling Jawf and Marib, east of Sanaa, killed 12 people, raising the death toll from clashes since Thursday to 34.
20 soldiers and tribesmen and 14 rebels were killed, the sources said.
Rebels used tanks and artillery against government forces and tribesmen defending the area, tribal sources said, insisting that the offensive was repelled.
AFP was unable to verify the death toll with independent sources or to obtain rebel confirmation of their deaths.
Analysts say the rebels, also known as Zaidis or Ansarullah, are trying to establish themselves as the dominant political force.
They are attempting to do this in the northern highlands, where Shias are the majority community in the mainly Sunni Arabian Peninsula nation.
The Shia Huthis held protests throughout much of August to push for the government's resignation.
They have rejected overtures from President Abdrabuh Mansur Hadi to name a new prime minister, replace the government and reduce a disputed fuel price hike.