Lise Grande’s statement comes amid ongoing fighting in the Arabian peninsula State, where 22 million people are in need of aid and protection; three-quarters of the entire population.

Around 8.4 million of this number are severely food insecure and at risk of starvation, according to UN Office for the Coordination of Humanitarian Affairs (OCHA).

OCHA has warned repeatedly of the risks to ordinary Yemenis of being caught up in crossfire, since a military campaign intensified, involving a Saudi-backed international coalition and Houthi opposition forces which escalated in March 2015.

Since then, according to the UN human rights office, OHCHR, 6,439 civilians have been killed and more than 10,000 have been injured.

In response to the threat of military attack, humanitarian agencies had developed “contingency plans”, he added.Speaking to journalists in Geneva on behalf of Ms Grande, Jens Laerke said that in a “prolonged worst case (scenario), we fear that as many as 250,000 people may lose everything - even their lives”.

The country’s already weak infrastructure has also suffered tremendous damage, including to massive portside cranes in Hodeidah; a city which is “the single most important point of entry for food and basic supplies” for the whole country, Laerke told reporters.

Close to 70 per cent of Yemen’s imports, including commercial and humanitarian goods, enter through Hodeidah and Saleef to the north.

As many as 600,000 people live in and around Hodeidah, Mr Laerke continued, before repeating the UN Humanitarian Coordinator’s comments that the Red Sea port city needed to stay open to prevent famine and “a recurrence of the cholera epidemic”, that began in October 2016.

By the end of January 2018, the number of suspected cases had risen to more than one million, according to the World Health Organization (WHO).

In addition to concerns for civilians around Hodeidah, needs in Yemen remain massive, said Laerke who described ongoing emergency as “the worst humanitarian crisis in the world”.

“Across the country, people are desperate for food, medical help and protection,” he explained. “This is why humanitarian organizations have dramatically ramped up the amount of assistance we are providing.”

OCHA/Giles Clarke