Already high malnutrition levels are expected to sharply increase throughout Yemen, a United Nations Children's Fund (Unicef) representative said in Geneva on 9 April.

"We expect in the coming weeks there to be an upsurge in malnutrition across the country, be it in areas of conflict or not, because it was already a country where 60% of the population lived under the poverty line, that is not going to get any better, people's revenues are going down, the cost of living is going up and government services are weakened if not falling apart," Julien Harneis said in an interview.

Harneis said chronic malnutrition has always been a problem in Yemen but in the past five years, Unicef along with its partners and other organisations managed to reduce the rate significantly from 65% to 48%.

He said rates of acute malnutrition in children could soar within weeks and threaten the lives of more than a quarter of a million children in Yemen.

"Couple of years ago, we had about 280,000 children who were severely and acutely malnourished. Now we have been able to reduce that to about 160,000 by the end of last year. The conditions now are worse than they were then. So I can't give a number to it, but it's very worrying," Harneis said.

Aid agencies have struggled to fly emergency supplies into the country, already one of the poorest in the Arab world.

A plane loaded with 16 tonnes of medical supplies had to turn back in mid-air because the window for landing at Sana'a closed at noon, a spokeswoman for the International Committee of the Red Cross said.

Harneis revealed the UN children's agency has tried for a week to get an aid flight in. He said: "For the last week, every day we've been trying to get a plane in and every day there has been a different problem just pop up and it's that combination that makes it so difficult, so we need to find a better solution that's more, more reliable and foreseeable."