Rockets fired by Houthi militiamen killed 14 civilians, most of them children, as fighting intensified for control of Yemen's third largest city, Taiz, residents said on Monday.

The Saudi-led coalition opposing the Houthis also launched air raids on military bases and Houthi positions in the southwestern city during the fighting, residents said, but no casualties were reported.

Fighters loyal to Yemen's exiled government have been contesting control of Taiz - Yemen's cultural capital - with the Houthis since April. Hundreds of combatants and civilians have been killed.

"The situation is awful and the fighting is happening on many fronts. All the hospitals have closed except for one, so there's a shortage of medical care. Two rockets fell on the Deluxe neighborhood, killing 14 people, among them women and children," Taiz resident Abdul Aziz Mohammed said.

"Taiz is being devastated."

The Saudi-backed government declared Taiz a "disaster area" in a statement released late on Monday and urged the international community and the U.N. Security Council to intervene to stop the bloodshed, the news agency that leans toward the exiled government said.

"The government will present a letter to the Security Council in New York and the High Commissioner for Human Rights in Geneva," Human Rights Minister Ezzeldin al-Asbahi, said in the statement.

The World Health Organization said on Monday it was coordinating a rapid response to provide emergency health access to the injured due to the growing humanitarian crisis in Taiz and Hodeida, saying there were more than 350 casualties reported in Taiz in the past week alone.

The northern-based Houthis, a Shi'ite Muslim group, took control of Yemen's capital Sanaa last September. Arab countries intervened in the conflict in March to halt a Houthi advance into the south which caused the Saudi-backed government to flee to Riyadh from its refuge in the southern port of Aden.

Months of air strikes and arms deliveries by the rich Gulf states to government loyalists began to pay off last month, when they seized back Aden and made surprise gains toward Yemen's north and Sanaa.

Gulf Arab states view the Houthis as a proxy for their archrival, Iran, but the group says it is fighting a revolution against a corrupt government beholden to the West.

Coalition warplanes on Friday killed 65 people in Taiz, most of them civilians, aid group Medecins Sans Frontieres said.

The United Nations is working to broker a political compromise to end the civil war which has killed more than 4,300 people and avoid a showdown in the Houthis' northern heartland.

Reuters