Fierce clashes broke out Saturday between pro-government tribesmen and Shiite Huthi rebels near the Yemeni capital, as the president vowed that authorities will not tolerate any violence.
The Huthis -- also known as Ansarullah -- have advanced out of their northern mountain strongholds towards the capital in a suspected attempt to expand their sphere of influence as Yemen is reorganised into six regions.
Clashes using machine guns and medium weapons raged in the villages of Darwan, Bani Maymun, Al-Jaef and Al-Maamar, in the northern town of Hamdan, around 10 kilometres (six miles) from Sanaa International Airport, tribal and army sources said.
Further north in Amran province, tribal and military sources said that "fierce clashes" pitting troops and Huthi militants raged late Friday.
The sources spoke of "dozens" of casualties but AFP could not immediately verify the toll.
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Meanwhile, in a speech marking the start of fasting holy Muslim month of Ramadan, President Abdrabuh Mansur Hadi denounced the violence.
"We will not allow any acts of violence here and there by any party trying to undermine security," Hadi said in a statement carried by the official Saba news agency.
"All parties must comply with agreements reached to resolve latest tensions and fighting in Amran, Hamdan, Arhab, and Bani Matar" in the north, he said.
Huthis have been battling the central government for years from their Saada heartland, complaining of marginalisation under former president Ali Abdullah Saleh, who stepped down in 2012 after a year-long uprising.
Clashes erupted anew earlier this month in the north, ending an 11-day truce agreed after mediation backed by United Nations envoy Jamal Benomar.
The rebels say a federalisation plan agreed in February following national talks as part of a political transition would divide Yemen into rich and poor regions.
They seized areas of Amran province in fighting with tribes in February that killed more than 150 people.