At least 40 people have been killed in three days of fighting between Shia Muslim rebels and Sunni tribesmen, as sectarian fighting draws closer to the capital Sanaa.
Fighting in al-Jawf province, 140km northeast of Sanaa, claimed more than 30 lives on Friday and Saturday before government mediators managed to broker a truce.
Fighting was still raging on Sunday in Hamdan, an area 30km northwest of Sanaa, with more than 10 people killed, officials on both sides said.
A local official called on government mediators to try to stop the fighting and warned in a statement carried by Yemeni media that failure to do so would result in a "bloodbath".
The Houthis, who control much of the northern Saada province bordering Saudi Arabia also blew up a three-storey Sunni religious education centre in Hamdan on Sunday, local tribal sources said.
Houthi fighters arrived in Hamdan from northern Yemen to safeguard access from their northern stronghold of Saada to Sanaa, where they have large following, tribal sources said.
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Fighters loyal to the tribe, who have repeatedly fought government forces since 2004, are trying to tighten their grip on the north but have denied wanting to enter the capital Sanaa.
Fighting in the north erupted last year when the Houthis accused Sunni Salafis at the town of Dammaj of recruiting foreign fighters to prepare an attack.
A government ceasefire was brokered between the warring factions before the Salafis finally agreed to leave the town.
Gulf Arab states and the United States have been particularly concerned about violence in the country as it shares a long border with oil exporter Saudi Arabia and its coast runs alongside Red Sea and Gulf of Aden shipping lanes.
The plan to transform Yemen into a six-region federation has been rejected by Houthis as they feel its splits the country into rich and poor regions.
The decentralisation plan has also drawn opposition from southerners who want a federal state made up of two provinces based on the former South Yemen.
On Sunday, Abd Rabbu Mansour Hadi ordered a panel to draw up the constitution for Yemen's new federation.
The 17-member panel, which includes four women, is expected to implement a decentralisation plan agreed at a national conference last year to create four regions in north Yemen and two in the south.