Fighting around the Yemen port city of Hodeida has resumed as a Saudi-led coalition tries to retake it from Shiite rebels.
Witnesses described heavy fighting to the city’s south, near its airport.
The Saudi-led coalition backing Yemen’s exiled government began the assault on the port city of Hodeida on Wednesday.
The Red Sea port is the main entry for food into a country already on the brink of famine.
The biggest offensive of the war in the Arab world’s poorest nation has raised warnings from aid agencies that Yemen’s humanitarian disaster could deepen.
The attack is aimed at driving out Iranian-aligned Shiite rebels known as Houthis, who have held Hodeida since 2015, and break the civil war’s long stalemate.
But it could set off a prolonged street-by-street battle that inflicts heavy casualties.
The fear is that a protracted fight could force a shutdown of Hodeida’s port at a time when a halt in aid risks tipping millions into starvation.
Some 70% of Yemen’s food enters via the port, as well as the bulk of humanitarian aid and fuel supplies.
Around two thirds of the country’s population of 27 million relies on aid and 8.4 million are already at risk of starving.
Early on Wednesday, convoys of vehicles headed towards the rebel-held city as heavy gunfire rang out.
The assault, part of an operation dubbed Golden Victory, began with coalition air strikes and shelling by naval ships, according to Saudi-owned satellite news channels and state media.
Bombardment was heavy, with one aid official reporting 30 strikes in 30 minutes.
The initial battle plan appeared to involve a pincer movement. Some 2,000 troops who crossed the Red Sea from an Emirati naval base in the African nation of Eritrea were awaiting orders to move in from the west after Yemeni government forces seize Hodeida’s port, Yemeni security officials said.
Emirati forces with Yemeni government troops moved in from the south near Hodeida’s airport, while others sought to cut off Houthi supply lines to the east, the officials said.
Yemen’s exiled government “has exhausted all peaceful and political means to remove the Houthi militia from the port of Hodeida”, it said in a statement. “Liberation of the port of Hodeida is a milestone in our struggle to regain Yemen from the militias.”
Four Emirati soldiers were killed in Wednesday’s assault, the United Arab Emirates’ state-run news agency said.
The Houthi-run Al Masirah satellite news channel claimed rebel forces hit a Saudi coalition ship near Hodeida with two missiles.
Forces loyal to Yemen’s exiled government and fighters led by Emirati troops had neared Hodeida in recent days.
The port is 90 miles south-west of Sanaa, Yemen’s capital, which has been in Houthi hands since September 2014. The Saudi-led coalition entered the war in March 2015.
The United Nations and other aid groups have already pulled their international staff from Hodeida ahead of the assault.
The port has remained open, however. Several ships arrived in recent days, including oil tankers, and there was no word from the coalition or the UN to stop work, according to a senior port official.
Aid groups nevertheless warned of disaster.
More than 10,000 people have been killed in Yemen’s civil war, which has displaced two million others and helped spawn a cholera epidemic.
Saudi-led air strikes have killed large numbers of civilians and damaged vital infrastructure.
The UN and Western nations say Iran has supplied the Houthis with weapons, from assault rifles to the ballistic missiles they have fired deep into Saudi Arabia, including at the capital, Riyadh.
The coalition has blocked most ports, letting supplies into Hodeida in co-ordination with the UN.
The air campaign and fighting have disrupted other supply lines, causing an economic crisis that makes food too expensive for many to afford.