Half of Yemen's population - some 14 million people - could soon be facing pre-famine conditions, meaning they are completely reliant on external food sources, according the UN Office for the Coordination of Humanitarian Affairs.

Briefing the UN Security Council this week, Mark Lowcock, the UN's humanitarian chief, said the situation in the country was worsening.

“There is now a clear and present danger of an imminent and great big famine engulfing Yemen: much bigger than anything any professional in this field has seen during their working lives," he said. 

Lowcock said that while he had previously issued warnings of an imminent famine in Yemen at the beginning of last year and again last November, the situation now was "much graver than on either of those two occasions".

The estimate of 14 million people is three million higher than was estimated in September.

Lowcock said the toll from years in which millions of people have been surviving on emergency food assistance for years was already "unbearably high".

"The immune systems of millions of people on survival support for years on end are now are literally collapsing, making them – especially children and the elderly – more likely to succumb to malnutrition, cholera and other diseases," he said.