Saudi Arabia and the United Arab Emirates have launched an assault on Yemen's port city of Hudaida, in the biggest battle of a three-year war between a Saudi-backed coalition and Iranian-aligned Houthi rebels. The United Nations says the attack exponentially puts a quarter of a million people at risk.

Last week, the UN said that in a worst-case scenario as many as 250,000 people could be killed in an offensive against Hodeidah.

"I am extremely concerned about military escalation in #Hodeida & their humanitarian & political impact. We're in contact with parties to avoid further escalation. We call on them to exercise restraint & engage with political efforts to spare Hodeida a military confrontation," the office of the UN's Yemen envoy Martin Griffiths said in a tweet on Monday.

The exiled government before the launch of the attack said, "We have exhausted all peaceful and political means to remove the Houthi militia from the port of Hudaida", in a statement. "The liberation of Hudaida port is a turning point in our struggle to recapture Yemen from the militias that hijacked it to serve foreign agendas," the statement added.

"The liberation of the port is the start of the fall of the Houthi militia and will secure marine shipping in Bab al-Mandab strait and cut off the hands of Iran, which has long-drowned Yemen in weapons that shed precious Yemeni blood."

The Saudi-led coalition launched ground attacks on the city's airport and other neighbourhoods in the south-eastern part of the city, with air and naval support, General Mohsen Al Khosrof of the Yemeni National Army (YNA) told CNN.

The YNA and the coalition are fighting on behalf of the internationally recognized government, which is trying to squash an insurgency by Iran-backed Houthi rebels.

A UAE military ship has been attacked by Houthi rebels and is currently on fire in the Red Sea off the coast of Hudeida, according to two senior Yemeni-Houthi military commanders. UAE state media has also reported that four Emirati soldiers had died fighting in Yemen, though the article did not specify whether their deaths are related to the attack on the ship.

The Red Sea port is the only port under Houthi control, situated about 150km southwest of the capital, Sanaa. According to Dubai-based Al Arabiya, Yemeni troops have gained control of the city's southern district of Nekheila.

The Hudaida port is crucial for the flow of food supplies into a country that is on the brink of famine.

(The above story first appeared on LatestLY on Jun 14, 2018 08:37 AM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).