SANAA - Ten Yemeni soldiers were killed and 20 wounded on Thursday in an attack on an army roadblock in Saada province in the northwest of the country, a security source said.

The assault was presumed to have been carried out by Zaidi rebels, he added.

"Violent clashes are taking place in the Rizamat region" where the checkpoint attack was reported said the source, who requested anonymity.

Thursday's toll raised to at least 22 the number of soldiers killed in fighting between the army and Zaidi fighters in Saada province since rebel attacks resumed earlier this week.

The ruling General People's Congress (GPC) of President Ali Abdullah Saleh said on its website on Wednesday that five soldiers, including an officer, were killed in "terrorist attacks led by members of the (rebel) group."

Zaidi rebels are suspected of being behind attacks on Saturday and Sunday against army and police in the Saada region near the Saudi border which left seven soldiers dead and 20 others wounded.

On Monday Saleh called on the rebels to lay down their arms and surrender.

"Those saboteurs and terrorists who belong to (tribal Zaidi leader) Abdul Malek al-Huthi should hand in their heavy and medium weaponry to the (army) command in the Saada region," he said in an address to military commanders.

There has been no official indication of rebel losses, but the security source said on Thursday that "three rebels were killed on Wednesday at a village in Saada province."

The Huthi tribe led a rebellion against government forces in 2004 and 2005 that left around 700 dead and hundreds more wounded. Since then there have been intermittent outbreaks of fighting.

One rebel leader, Abdel Malak al-Huthi, confirmed on Thursday that threats had been made against Jews in the village of Al Salem in Saada province to make them leave.

"These Jews have a problem with the other inhabitants of the region, who have complained about them," he told the Arabic-language satellite television channel Al-Jazeera.

"The people have demanded that these Jews leave because they have provoked damage... by their admitted meddling in regional affairs and their moral corruption," Huthi said.

Israel vowed on January 22 to investigate reports that Jews in Yemen had received death threats.

Sanaa said in April 2005 it had crushed the Zaidi "Young Believers" rebellion led by Badreddin al-Huthi after his son Hussein was killed by govenment forces the previous September.

The Zaidis are an offshoot of Shiite Islam dominant in northwestern Yemen, but form a minority in the mainly Sunni country.

The rebels reject as illegitimate the regime which seized power in a 1962 coup known as the September 26 revolution, overthrowing a Zaidi imamate.