The UN mission in Yemen's Houthi-held port of Hodeida expressed "great concern" on Tuesday over claims it was being used for military purposes and demanded access for an inspection.

The United Nations Mission to Support the Hodeida Agreement (UNMHA) said the port was vital for the impoverished country, where a seven-year war has pushed millions to the brink of famine.

The Saudi-led coalition fighting alongside government forces accused the Iran-backed Houthisof militarising the Red Sea ports and threatened to attack them, after the insurgents seized a United Arab Emirates-flagged ship last week.

"UNMHA reminds the parties that Hodeida ports are a crucial lifeline for millions of Yemeni people," it said in a statement.

The coalition says the seized vessel, the Rwabee, was carrying medical supplies but the Houthis insist it was a military ship.

The hijacking on January 3 raised fears that the conflict could spill over into the Red Sea, a vital route for Gulf oil and cargo shipments.

It could also have severe consequences for Yemen, which the UN has said is facing the world's worst humanitarian crisis, if it draws attacks on Hodeida.

"UNMHA has requested as part of its mandate to undertake an inspection," the statement said, adding that protecting the ports was "in the interest of the Yemeni people".

The UN mission is aimed at preserving the often ignored Hodeida Agreement, a ceasefire for the port agreed at peace talks in Sweden in 2018.

"There are no sustainable solutions to be gained from military escalation," the UN special envoy for Yemen, Hans Grundberg, said in a statement.

"The parties can and should engage in a sustained political dialogue aimed at de-escalating the violence and finding a way towards a negotiated comprehensive solution," he added.

Yemen's civil war began in 2014 when the Houthis seized the capital Sanaa, prompting Saudi-led forces to intervene to prop up the government the following year.

The UN has estimated the war killed 377,000 people by the end of 2021, both directly and indirectly through hunger and disease.

-AFP