Protesters demonstrate against the deployment of armed militia of the Shiite Houthi movement in Sanaa December 26, 2014.

Twelve people have been killed in clashes between tribesmen and Shiite rebels north of the capital Sanaa, the Associated Press reported Yemeni security officials and tribal leaders as saying on Sunday.

They say Shiite Houthi rebels went to the Arhab district late Saturday to search the home of a tribal chief whom the rebels suspected of being allied with the Sunni Islamist al-Islah party, with which the rebels are at war.

Clashes erupted when locals resisted the search, leaving nine rebels and three tribesmen dead.

The officials and tribal leaders say the rebels later destroyed the house, which was believed to be empty. They spoke on condition of anonymity because they were not authorized to brief reporters.

The Houthis swept down from their northern stronghold and captured the capital Sanaa in September.

On Saturday, the Houthis vowed to press ahead with an offensive it launched in September to consolidate its grip across Yemen, despite fierce resistance from Sunni tribes and Al-Qaeda.

The Arabian Peninsula country has been rocked by instability since the Houthis seized control of Sanaa in September.

They have since expanded their presence in central and western Yemen, but have met fierce resistance from powerful Sunni tribesmen backed by fighters from Al-Qaeda.

“The Yemeni people is determined to pursue its revolution… and combat corruption,” Houthis’ chief Abdulmalik al-Huthi said in a statement published by Yemeni media.

He said he will also push ahead with the offensive to “guarantee security” and “put an end to political tyranny” — repeating slogans used by the Huthis to justify launching their campaign in September.

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