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By Mohammed Ghobari
SANAA, May 4 (Reuters) - Qatari mediators returned to Yemen's volatile northern province of Saada on Sunday, hoping to salvage a truce brought to the verge of collapse by a mosque bombing and days of clashes between rebels and the army.
Rebels led by Abdul-Malik al-Houthi seized a government building in the town of Manbah after clashes on Saturday and the army has surrounded the compound, local tribal sources said. Tribes were mediating an end to the standoff.
"The Qataris and the government delegation have now returned to Saada amid continued to tensions," the chief rebel negotiator Saleh Habra told Reuters.
The situation in Saada remained tense after a bomb killed 15 people outside a mosque on Friday, with security checkpoints around the city and few people on the streets, he said.
Yemen, one of the poorest countries outside of Africa, 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 in Saada on Friday and investigations suggested that followers of Houthi, who belong to the Zaydi sect of Shi'ite Islam, were behind the attack, a charge Houthi denies.
Fighting has raged on and off in Saada since a conflict broke out in 2004 between government forces and Houthi's rebels.
A Qatari-brokered truce ended six months of intense fighting in June but violence has increased in recent weeks as a lack of trust on both sides and disagreements over the release of prisoners and handover of arms threaten to undermine the deal.
The ceasefire agreement committed Yemen to rebuild rebel areas and required rebels to give up their heavy weapons but did not include a clear mechanism for implementation.
Qatari mediators face a tough task salvaging the deal with both sides claiming the other is not serious about making peace.
"There is a chance (for peace) but it requires strong and serious will from the political leadership," Houthi told Al Jazeera TV. "We have the will and we are serious ... the problem is that the other side conducts continual assaults on us."
The rebels are worried that if they give up their weapons and prisoners first, they will be attacked. The government is reluctant to release its prisoners since a state amnesty that freed 600 rebels in 2006 failed to end the revolt.
Hundreds of people have been killed and thousands have fled their homes in Saada since the conflict began.
Yemeni officials say the rebels want to return to a form of clerical rule prevalent until the 1960s. The rebels, who want Zaydi schools and oppose the government's alliance with the United States, say they are defending their villages against what they call government aggression.
Sunni Muslims form a majority of Yemen's 19 million population, while most of the rest are Zaydis, the closest of all Shi'ite sects to mainstream Sunni Islam.
Apart from security, Yemen is also grappling with dwindling oil and water resources, unemployment, corruption and a large community of Somali refugees. (Writing by Lin Noueihed; editing by Sami Aboudi)