Several formerly neutral tribes in northern Yemen have joined pro-government forces in fighting the Houthi militia.
The Hajoor tribe have been fighting the Iran-backed rebels in the mountainous areas of Kushar district in the northern province of Hajjah for more than a month.
Tribal leaders held a meeting with the government leader of the province, Abdul Kareem Al Sunaini, who pledged to help them fight the insurgents.
A source in the Hajoor tribes said the Houthis had been sending more troops to the area to take control of Kushar.
At the meeting, other prominent tribes in Hajjah province agreed to assist the Hajoor in their fight, including the Al Yehya tribe, the source added.
Pro-government troops arrived in Hajjah province on Sunday to break a siege imposed by the Houthis around the Hajoor, a military source said.
Four military battalions from the Yemeni army were sent to the provinces from Jazan in Saudi Arabia, the source said.
Meanwhile, intensified clashes raged on Sunday between the Houthis and the Hajoor in the villages of Jumana, Bani Rassam and Shaws in southern Kushar.
The Houthis have sent fresh troops to the battleground and begun shelling civilian homes using tanks, artillery and mortars, journalist Fayez Al Sadi said.
“About 1000 families have displaced to the neighbouring areas to escape the aggressive Houthi shelling," Al Sadi said. "The majority of the displaced families are staying in schools."
