"I am happy to say that following intensive efforts... we have reached a ceasefire" between the sides fighting in Sa’ada province, Jamal Benomar told reporters on Monday.

A Red Cross convoy entered the town of Dammaj, where a fighting was underway between the Salafis and the Houthis, and the International Committee of the Red Cross said its teams had evacuated 23 critically wounded people.

"There are still more wounded people in need of treatment, and we hope to be able to come back for them," the ICRC director in Yemen, Cedric Schweizer, said in a statement.

Benomar said Yemeni President Abdrabuh Mansur Hadi had sent a special plane to evacuate the wounded.

"I hope this ceasefire will be permanent, and I hope that efforts will follow to find a solution for the roots of this problem," Benomar said, while also warning the conflict "threatens the security of Yemen".

"Large groups of gunmen are being mobilized from different areas. This would have serious security implications," he added.

Dammaj, where a school for Salafi preachers has operated since the 1980s, has been the scene of frequent clashes between the extremists and the Houthis, for whom Sa’ada is a stronghold.

Tribal sources have said at least 11 people were killed in fighting last week, but Salafis put the death toll at around 50.

On Saturday, the Defense Ministry's news website reported a ceasefire and said troops had been deployed in areas evacuated by the rival sides.

A statement by the Houthis said that the foreign-backed Salafis "transformed the center of Dammaj into a real barracks for thousands of armed foreigners."

The Houthis, who are members of the Zaidi Shia community, rose up in 2004 against ex-president Ali Abdullah Saleh's government, accusing it of marginalizing them politically and economically.

BA/BA