As the fighting continues, the Saudi led-coalition unveiled a "multi-faceted plan" to protect civilians in Hodeidah, which allegedly includes aid shipments from Saudi Arabia's southern city of Jizan and the UAE's capital, Abu Dhabi, AP reported.
The UK is working with the UN, NGOs and the Coalition to respond to the humanitarian situation.
The number at risk of starvation could more than double to more than 18 million by year end, unless the situation improves.
Pro-government troops began the offensive to retake the rebel-held port city, which is a key aid hub, on Wednesday, despite mounting worldwide fears about the humanitarian fallout.
The assault marks the first time the Arab states have tried to capture such a heavily-defended major city since joining the war three years ago against the Iran-aligned Houthis, who control the capital Sanaa and most of the populated areas.
U.S. Secretary of State Mike Pompeo said Wednesday he has talked with leaders of the United Arab Emirates, part of the Saudi coalition force, and made clear the desire to address security concerns "while preserving the free flow of humanitarian aid and life-saving commercial imports".
The conflict in Yemen has raged since late 2014, when the Houthis and allied forces seized north-western parts of the country, including the capital Sanaa, and eventually forced President Abdrabbuh Mansour Hadi to flee overseas.
Western countries, particularly the United States and Britain, have quietly backed the Arab states diplomatically and sell them billions of dollars a year in arms, but have mostly avoided direct public involvement so far in the Yemen conflict.
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. Both Iran and the rebels deny this. "The coalition warship was burned and other battleships retreated after seeing the fire", the statement said, according to Saba news agency.
The United Nations had been trying to get the parties to reach a deal to avert an attack.
An estimated 600,000 people live in the area.
With anti-government forces embedded in the city, military victory in Hodeida "seems a very tall order" and an assault on the city would only lead to further bloodshed, he warned. An alliance of Yemeni forces supporting the internationally recognised government is leading the ground assault.
Al Arabiya is believed to be at least partially owned by Saudi Arabia's government.
"The liberation of the port is the start of the fall of the Houthi militia and will secure marine shipping in the Bab al-Mandab strait and cut off the hands of Iran, which has long drowned Yemen in weapons that shed precious Yemeni blood", Yemen's Arab-backed government-in-exile said in a statement. But in the last few weeks, the rebel side has lost a lot of fighters and commanders.
It has argued repeatedly that a Hudaydah offensive can be mounted quickly and effectively, leaving the port functioning at a higher capacity. But it could set off a prolonged street-by-street battle that inflicts heavy casualties.
In reality, families in Hudaydah are already starving and desperately relying on humanitarian aid. "Their total support for Saudi Arabia and its allies is making the world's worst humanitarian crisis even more severe". Already, Yemeni security officials said some were fleeing the fighting.
"Any attack on or significant, long-term disruption of operations of the port will have catastrophic consequences for the people of Yemen", Frank McManus, the International Rescue Committee's country director in Yemen, told ABC News.
"The battle for Hodeidah will nearly certainly result in a huge loss of civilian life and damage to vital infrastructure", said Tamer Kirolos, Yemen Country Director for Save the Children.