Clashes break out in northern Yemen as truce falters

People gather at the scene of a bomb blast outside the Bin Salman Mosque in the north-western Yemeni city of Saada May 2, 2008. About 15 people were killed and dozens wounded on Friday in the bombing in volatile Saada that officials blamed on followers of rebel leader Abdul-Malik al-Houthi. (REUTERS/Yemen News Agency/Handout)

SANAA (Reuters) - Clashes erupted between Yemeni forces and rebels led by Abdul-Malik al-Houthi on Saturday, dealing a new blow to a faltering ceasefire a day after a mosque bombing killed 15 people in the northern city of Saada.

Government forces killed five rebels, members of the Zaydi sect of Shi'ite Islam, in Saada, while rebels surrounded a government compound in nearby Manbah, local sources said.

Hundreds of Yemenis demonstrated in Saada earlier in the day in show of anger against the attack that appeared to target army officers but killed a woman, two children and other civilians.

Yemen has witnessed attacks by different groups targeting everything from tourists to government offices in recent years, but attacks on mosques were virtually unheard of until Friday.

A security source said several suspects had been detained at a checkpoint in Saada and investigations suggested that Houthi's followers were behind the attack.

Houthi denies the charge but fighting has raged on and off in Saada since a conflict broke out in 2004 between government forces and the rebels he leads.

A Qatari-brokered truce ended six months of intense fighting in June but violence has increased in recent weeks as disagreements over the release of prisoners and handover of arms threaten to undermine the deal.

Friday's bomb, which was hidden in a motorcycle outside the door of the Bin Salman Mosque and detonated as worshippers left, came as a Qatari delegation was meeting officials in Yemen to try to prevent a total collapse of the ceasefire.

"These crimes and violations are virtually daily and their perpetrators, the insurgent elements, have not implemented any terms of the agreement to end the strife of the insurgency but have refused to hand in their arms or come down from their positions in the mountains," the governor of Saada, Motahhar Rashad, told Yemen's Saba news agency.

The ceasefire agreement committed Yemen to reconstruct rebel areas and required rebels to give up their heavy weapons.

Hundreds of people have been killed and thousands have fled their homes in Saada since the conflict began. Seven Yemeni troops were killed on Tuesday in an ambush by the rebels and two were wounded in clashes late on Friday.

Last month gunmen killed Yemeni lawmaker Saleh al-Hindi, who was known to support government efforts to subdue the rebels.

Sunni Muslims form a majority of Yemen's 19 million population, while most of the rest are Zaydis.

Yemeni officials say the rebels want to return to a form of clerical rule prevalent in the country until the 1960s. The rebels say they are defending their villages against what they call government aggression.

One of the poorest countries outside Africa, Yemen is struggling with several conflicts on top of its economic ills.

As well as fighting the Houthi revolt, the ancestral home of Osama bin Laden has cooperated with the United States since the September 11, 2001 attacks on U.S. cities.

In the south, anger over perceived northern depredations exploded into riots this year that threatened to weaken the 1990 accord that united traditionalist north Yemen with the Marxist south.

(Additinal reporting by Mohammed Ghobair, Writing by Lin Noueihed; Editing by Dominic Evans)