Shiite rebels battled pro-government tribes and Sunni Islamists close to the Yemeni capital through the night before a fragile truce was restored on Thursday, tribal sources said.

The rebels have been pushing out from their stronghold in the mountains of the far north to other Zaidi Shiite majority areas nearer to the capital in a bid to expand their hoped-for autonomous unit in a promised federal Yemen.

But they have met resistance from Zaidi tribes loyal to the historic leading family of the huge Hashid confederation and their Sunni Islamist allies in the Islah party.

The fighting erupted late Wednesday in the Arhab district -- just 35 kilometers (20 miles) north of the capital and close to Sanaa international airport -- shattering a fledgling truce, a tribal chief said.

The tribal chief accused the rebels of starting the fighting, breaking the truce agreed after they made major advances, overrunning the home base of the Al-Ahmar clan, the Hashid's increasingly contested leading family, at the weekend.

But the rebels, known as Huthis from the name of their leading family, or Ansarullah (Partisans of God), accused Islah party militia of breaking the agreement.

"The truce that was agreed on Saturday between the Huthis and the tribes of Arhab has collapsed due to a broad offensive by the Huthis," the tribal chief said, asking not to be identified.