Yemeni government troops backed by a Saudi-led coalition aims to seize the heavily defended city of Hudaida quickly enough to avoid interrupting aid to millions facing starvation.
Troops backed by a Saudi-led coalition stormed the airport compound of Yemen's main port city Hudaida on Tuesday after fierce battles with Iran-aligned Houthis fighting to defend their sole port, residents and Yemeni military sources said.
The capture of the airport would be an important gain for the coalition led by Saudi Arabia and the United Arab Emirates (UAE) who have said they can seize the heavily defended city quickly enough to avoid interrupting aid to millions facing starvation.
"They have stormed the airport," an anti-Houthi Yemeni military source told Reuters.
A resident also said the compound had been stormed.
"This is the first time we hear the clashes so clearly. We can hear the sound of artillery and machine gun fire," the resident, who requested anonymity, told Reuters, adding that warplanes bombarded the airport earlier in the morning.
The Western-backed alliance launched the onslaught on Hudaida seven days ago in order to turn the tables in a long-stalemated proxy war between Saudi Arabia and Iran that has compounded instability across the Middle East.
The upsurge in fighting has wounded and displaced dozens of civilians and hampered the work of aid groups in the port city, which is a lifeline for millions of Yemenis.
The United Nations says 22 million Yemenis depend on aid, and 8.4 million are on the verge of starvation.
UAE Minister of State for Foreign Affairs Anwar Gargash said on Monday that the coalition was taking a measured approach to minimise risks to civilians, and allowing the Houthis an escape route inland to their bastion in the capital Sanaa.
The Arab states say their aim is to seize the airport and port and to avoid street fights in the city centre.
Gargash said the coalition was counting on Martin Griffiths, the UN special envoy for Yemen who arrived in Sanaa on Saturday, to secure a Houthi agreement to leave Hudaida.
A member of the Houthi politburo, Mohammed al Bukhaiti, denied the talks centred on handing over the port city "because this request is unrealistic".
"During all his visits, the envoy has discussed a comprehensive political solution that addresses ... all the fronts and not just Hudaida only," he told Reuters by telephone.
The coalition intervened in Yemen's war in 2015 to try and unseat the Houthis, restore the internationally recognised Yemeni government in exile and thwart what Riyadh and Abu Dhabi see as Iran's expansionary ambitions in the region.
The Houthis, who control most of the populated areas in the unstable nation of 30 million people, deny the Arab states' assertions they are puppets of Iran. They say they came to power in a popular revolt against corruption and are protecting the country from foreign invasion.
Losing Hudaida would deal a serious blow to the Houthis by cutting off their main supply line. It could also give an edge to the Western-backed military alliance which, despite superior weaponry and firepower, has failed to defeat the group in a war that has killed 10,000 people.