By Mohammed Mukhashef
ADEN (Reuters) - A shaky truce took hold in Yemen on Monday under a U.N.-backed effort to end a war that has made the country a front in Saudi Arabia's region wide rivalry with Iran and caused one of the world's worst humanitarian crises.
The war-damaged capital Sanaa spent a quiet night, witnesses said, but residents said fighting flared in the southwestern city of Taiz soon after the planned start of the cessation of hostilities at 2100 GMT on Sunday.
The government, which backed by a Saudi-led Arab coalition, and its Iranian-allied Houthi adversaries blamed each other for the violence in Taiz, a city that has been hit hard by the war.
The government accused Houthis of using heavy artillery within moments of the start of the truce, while the Houthis said coalition warplanes staged three strikes on the city.
"People are no longer able to live because of the war that destroyed everything," said Shawqi Abdullah, a 30-year-old taxi driver in Sanaa, which lies in the north of the country.
"We had a calm night with no planes flying or fear of bombs. And we hope the calm will continue and the war ends."
The main southern port city of Aden, where coalition fighters expelled Houthi forces in July, was also quiet.
The halt in fighting precedes peace talks set to begin on April 18 in Kuwait under U.N. auspices between the government and the Houthis foes aimed at ending a conflict that has killed more than 6,200 people and displaced millions.
The coalition began a military campaign in March last year with the aim of preventing Houthi rebels and forces loyal to Yemen's ex-President Ali Abdullah Saleh from taking control of the country.
The Houthis, who seized the capital Sanaa in September 2014 and now control tracts of Yemen with the help of forces loyal to Saleh, say they are part of a revolution against corruption.
Saudi Arabia and allied Sunni Muslim states fear that the Houthis, who belong to a Shi'ite sect, will spread the influence of their Shi'ite arch-rival Iran in the Arabian Peninsula.
The United Nations special envoy for Yemen said in a statement a committee of military representatives from both sides would work to make the truce hold.
"Now is the time to step back from the brink," Ismail Ould Cheikh Ahmed said.
The truce terms included commitments for unhindered access for relief aid to all of Yemen.
"This truce is in its early stages, violations may occur in the beginning, but we hope the next few hours will see more discipline towards the ceasefire," Yemen's foreign minister Abdel Malek al-Mekhlafi told pan-Arab TV channel al-Arabiya.
The conflict has caused a humanitarian disaster, with nearly half of Yemen's 22 provinces on the verge of famine, the U.N. World Food Programme said in March.
The U.N. Children's Fund said basic services and infrastructure were on the verge of total collapse.
(Additional reporting by Sylvia Westall in Dubai and Mohammed Ghobari in Cairo, Writing by Reem Shamseddine and William Maclean, Editing by Angus MacSwan)