Three Huthi Shia rebels were killed on Wednesday in an attack by Sunni Islamists in Yemen's northern Saada province, the rebels said, warning that the violence could escalate sectarian tensions.
The early morning attack took place in the northern town of Dammaj, a rebel stronghold where some 20 people were reported killed and at least 70 others wounded in attacks last week by Huthis on a Sunni religious institute.
"In a step that reveals their malicious intentions, [Sunnis] opened fire on us, killing three people," said a statement released by rebel chief Abdel Malek al-Huthi.
The statement warned that "these unprovoked attacks are unjustified and are aimed at igniting a sectarian war in the country."
On November 30, thousands of Sunnis rallied in the Yemeni capital Sanaa against the alleged siege of a religious school by Shia rebels in Dammaj.
A spokesman at the rally told AFP that 7,000 people, including women and children, were trapped in Dammaj, facing "daily bombings by Huthis."
He said at least 26 people had been killed since the beginning of the blockade including at least two Americans, a French citizen, a Russian and a number of Indonesians and Malaysians.
The Huthis are Zaidi Shia who complain of marginalization by the Sanaa government. Thousands have been killed since a rebellion began in 2004. A ceasefire was reached in February last year.