Houthi forces have fired such missiles at ships previously.

The Norwegian Refugee Council said in a statement the port remained open Thursday, citing information from the UN There were "four vessels filled with food and fuel at berth" and another five vessels at anchorage, it said.

For years, coalition leaders have clamored for the Pentagon, which already provides intelligence, midair refueling capabilities and munitions to the campaign, to greenlight an offensive for the port.

On Monday, the UN Security Council said it supported Griffiths' diplomatic efforts but did not specifically call on Saudi Arabia and the United Arab Emirates, whose troops are backing Yemeni forces, to refrain from attacking Hodeida.

The port city, home to 600,000 people, was captured by the insurgents in 2014 along with the capital Sanaa. "The coalition warship was burned and other battleships retreated after seeing the fire", the statement said, according to Saba news agency.

It receives anywhere from 70 percent to 80 percent of all aid shipments, including food, medicine and basic supplies that serve more than 20 million people in need - three quarters of the entire population.

Gunfire has erupted near Yemen's port city of Hodeida as a Saudi-led coalition's deadline expired for Shiite rebels there to withdraw. The aim is to box in the Houthis in Sanaa, cut their supply lines and force them to the negotiating table.

Over 10,000 people have been killed in Yemen's civil war, which has displaced 2 million more and helped spawn a cholera epidemic.

A draft for a United Nations peace plan for Yemen exclusively seen by Reuters calls on the Houthi movement to give up its ballistic missiles in return for an end to a bombing campaign from a Saudi-led coalition. Meanwhile, the UN and Western nations say Iran has supplied the Houthis with weapons from assault rifles up to ballistic missiles.

The Hudaida port is a vital lifeline that is crucial for the flow of food supplies into a country that is on the brink of starvation, as it serves the entry point for 70 percent of the country's imports.

Research carried out by Amnesty International prior to today's military operation, due to be published soon, shows that the Saudi Arabia-led coalition had been restricting or severely delaying commercial imports to the Red Sea ports, despite announcing in November 2017 that it had lifted its blockade. A Saudi-led airstrike in 2015 destroyed cranes at Hudaida. "We already gave the United Nations the chance to operate from this seaport, and (the Houthis) refused". Some 8.4 million people in Yemen face pre-famine conditions, according to the World Health Organization. The U.N. special envoy to Yemen, Martin Griffiths, has said the world body is talking to both sides to de-escalate.

However, coalition spokesman Colonel Turki al-Malki said they wanted to avoid a street war with the Houthis "for the safety of civilians".

Yemeni forces backed by troops from the United Arab Emirates launched the assault despite UN warnings of a "catastrophic humanitarian impact". "The British told us a week ago that the Emiratis and the Saudis had told them they would not enter the battle of Hodeidah without their agreement and assistance".

Saudi Arabia's ambassador in Washington Khaled bin Salman also on Tuesday said the retaking of Hodeida was critical, tweeting that the Iran-backed rebels posed a "growing threat" to maritime security. The US has been offering targeting information to the Saudi-led coalition, as well as refueling their warplanes, though its role in Wednesday's assault wasn't immediately clear.

Hours earlier, Yemeni exiled President Abd-Rabbu Mansour Hadi flew from the Saudi capital Riyadh to Abu Dhabi to meet UAE officials after a year of tense relationship that led to deadly clashes between Hadi's loyal southern forces and UAE-backed parties over control of the southern port city of Aden.

The Houthis deny they are Iranian pawns and say their revolt is against corruption and defending Yemen from invaders.