The United Nations has warned that thousands of Yemeni civilians were at risk in the western province of Hudaida after an increase in military clashes this month.

Since 2014, Yemen has been engulfed in a war between the internationally recognised government, supported by a Saudi-led military coalition, and the Iran-backed Houthi rebels that has triggered a devastating humanitarian crisis.

The latest clashes in the rebel-held Red Sea port city of Hudaida - the main gateway for food, fuel, and humanitarian aid to the rest of the country - are the most violent since a truce negotiated in the area by the United Nations came into force in 2018.

'Thousands of civilians at risk'

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said in a statement on Thursday that "concern is increasing" with "thousands of civilians at risk".

It added that preliminary reports showed that at least 700 people have been displaced by the recent fighting and that "there have already been civilian casualties".

At least eight civilians, mostly women, and children, were killed last week, and many houses and farms damaged, the UN said.

"Indiscriminate attacks on residential areas are a breach of international humanitarian law and must stop immediately," said Auke Lootsma, the UN's humanitarian coordinator in Yemen.

Two explosions rattled Hudaida city on Wednesday night, residents told AFP.