The assault on the airport of Yemen's main port city has been underway for the past four days as the Saudi-led coalition attempts to gain control of Hudaida, which is the main conduit for aid.
Houthi forces fought to keep control of the airport in Yemen's main port city of Hudaida on Sunday as Saudi-led coalition air strikes struck the compound.
"Coalition airplanes carried out more than 20 raids until now and shook the city," resident Akram Yihya said by telephone. "We can clearly hear fighting and missiles landing in an area near the airport."
TRT World's Sarah Balter reports.
About 20,000 troops, mostly Yemenis from various factions led by United Arab Emirates forces and backed by warplanes and Apache attack helicopters, have been fighting to dislodge the Iranian-backed Houthis since 2015.
The coalition wants to restore an internationally recognised government in exile and thwart what Riyadh and Abu Dhabi believe are arch-foe Iran's ambitions to dominate the region.
Losing Hudaida would cut supply lines from the Red Sea to their stronghold in the capital Sanaa.
The Western-backed military alliance which, despite superior weaponry and firepower, has failed to defeat the Houthis in a three-year war that has killed 10,000 people and created the world's most urgent humanitarian crisis.
As air raids pounded Houthi fortifications in the airport, Houthi fighters blocked the main road from Hudaida to Sanaa with mounds of earth and chunks of asphalt to prevent coalition troops from advancing.
"The air strikes and missiles are shaking the city's houses," said resident Khaled Sharaf.
People living near the airport said bullets were hitting their homes as fighting raged.
Civilians have already endured air strikes, port blockades, hunger and a cholera epidemic since the conflict erupted.
US President Donald Trump's withdrawal from Iran's nuclear deal and his embrace of nuclear state North Korea have added to Tehran's isolation and put pressure on the Islamic Republic to preserve its interests in Yemen and other Arab states.
Minister of State for Foreign Affairs Anwar Gargash said the military alliance led by Saudi Arabia and the UAE was taking into consideration a "fragile humanitarian situation," avoiding civilian casualties in addition to military calculations.
Gargash, speaking to reporters in Dubai on Monday, estimated the number of Houthi fighters in Hodeidah at between 2,000 to 3,000. He declined to reveal the size of coalition forces but said they had "numerical superiority."
The Houthis, mountain fighters who seized Sanaa in 2014, gained valuable experience in a series of guerrilla wars with Yemen's national army and a brief border war with Saudi Arabia.
Armed mostly with AK-47 assault rifles, they have advanced on sandal-shod feet and by pickup trucks in battles across Yemen, one of the world's poorest countries.
That may give them an advantage in street-to street combat if fighting extends to the densely populated neighbourhoods of Hudaida, a city home to around 600,000 people.
Riyadh has accused the Houthis of using Hudaida port to smuggle Iranian-made weapons, including missiles used to target Saudi cities — accusations denied by the group and Tehran.
Houthis rule the most populous areas of Yemen, a chronically unstable country, where many parties have been competing in a messy civil war, from loyalists of the late President Ali Abdullah Saleh to southern separatists to Al Qaeda.
The United Nations says the assault on Hudaida could trigger a famine imperilling millions of lives.
The UN Office for the Coordination of Humanitarian Affairs said that 4,458 households had been displaced in Yemen's flashpoint Hudaida province this month.
Many residents are bracing for more hardship as the warring sides dig in.
The meagre income that Yehia Sohail generated with occasional work at Hudaida’s port could soon vanish.
"I take the money to cover the needs of one day and that’s it, it’s done," he said, speaking outside his shack, built from corrugated metal, palm fronds and torn blankets.
"Now if the port closes, where will I go to work? When this siege comes and this disaster happens, where am I going to find work?"
His wife, Um Ahmed, said the family had no cooking gas. A motorcycle, their only means of transportation, had broken down. Sometimes strong rains and wind batter their tiny home.
"I have a young daughter who’s exhausted and sick and we can’t get her medication or anything, only the necessary food. If a war happens, what are we going to do?" she said.
UN talks with insurgents amid clashes
UN envoy Griffiths arrived in rebel-held Sanaa on Saturday for a second round of talks since taking the post in February.
Houthi representative Sharaf, however, accused the Saudi-backed government of "obstructing negotiations", saying the Hudaida offensive had foiled any potential peace talks in a statement carried by the rebels' Saba news agency.
Multiple rounds of UN-brokered talks between the rebels and the Hadi government have failed to find a solution to the conflict.
Griffiths, whose talks in Sanaa have been largely kept under wraps, is believed to be pressing the Houthis to cede control of the Red Sea port to a UN-supervised committee that would allow deliveries of commercial goods and aid to continue to flow.
On Saturday he called for restraint and said he was in contact with all the warring parties in a bid to halt the fighting.
The UN Security Council on Thursday demanded that Hudaida port be kept open to vital food shipments but stopped short of backing a Swedish call for a pause in the offensive to allow for talks on a rebel withdrawal.
UN human rights chief Zeid Ra'ad al Hussein has voiced concern that the onslaught could endanger millions of civilians.
Pope presses for talks
Pope Francis is pressing for negotiations involving the sides in the Yemen conflict so the humanitarian crisis doesn't worsen.
In public remarks Sunday, Francis said he was following "with worry the dramatic fate of the people of Yemen, already so exhausted from years of conflict."
He appealed to the international community so that "no effort be spared to urgently bring to the negotiating table the sides in conflict and to avoid a worsening of the already tragic humanitarian situation."