ADEN: Fighting between Yemen's warring parties in the gas-rich Marib region, the recognised government's last northern stronghold, intensified late on Saturday, three sources said, at a time the United Nations and the United States are pushing for a peace deal.
The Ansar Allah who has been battling a military coalition for over six years has been trying to seize Marib in an offensive described by Washington as the most serious threat to efforts to achieve a truce.
Battles had abated as diplomatic efforts ramped up in recent weeks, but three pro-government Yemeni sources said tens of fighters from both sides were killed in fighting after a fresh Ansar Allah assault that was met with intense coalition airstrikes.
Ansar Allah-run Al Masirah television channel said coalition warplanes conducted 13 strikes late on Saturday.
"The fighting continued until the early morning," one of the sources, a local official, said. "They are the heaviest in weeks."
Marib, which hosts some 1 million internally displaced people, has become the focal point of a war that has killed tens of thousands of Yemenis and pushed the Arabian Peninsula nation to the brink of famine.
The warring parties have been thrashing out terms for an UN-led proposal to remove restrictions on Ansar Allah-held ports and Sanaa airport to alleviate a dire humanitarian crisis and for a ceasefire that is needed to revive political negotiations last held in late 2018.
The Ansar Allah, whose hand would be strengthened in any future talks by taking Marib, have insisted the blockade be lifted before any truce talks. The coalition wants a simultaneous deal.
The military alliance intervened in Yemen in March 2015 after the Ansar Allah ousted the government from the capital Sanaa.
The Ansar Allah who have repeatedly launched cross-border missile and drone attacks on Saudi cities, largely intercepted, say they are fighting a corrupt system and foreign aggression.
Meanwhile, one government military official said, "These areas witnessed fierce fighting amid artillery shelling from both sides and intense coalition air raids."
Control of the oil-rich region of Marib would strengthen the Ansar Allah bargaining position in peace talks, but the battle has also raised fears of a humanitarian catastrophe, as many Yemenis had fled to the area to escape fighting in other parts of the country.
While the UN and Washington are pushing for an end to the war, the Ansar Allah have demanded the re-opening of Sanaa airport, closed under a blockade since 2016, before any ceasefire or negotiations.
As well as the bloody offensive in Marib, the Ansar Allah has also stepped up drone and missile strikes on Saudi targets, including its oil facilities. This month the outgoing UN envoy for Yemen Martin Griffiths told the Security Council his own efforts over the past three years to end the war had been "in vain".
The fighting has killed tens of thousands and left some 80 percent of Yemenis dependent on aid, in what the UN calls the world's worst humanitarian crisis. The war has also displaced millions of people and left many on the brink of famine.
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