United Nationsinfo-icon and Russian officials warned on Tuesday against any attack by Saudi-led coalition forces on the Houthi-held Yemeni port of Hodeidah, the aid lifeline for a country where millions of people are in desperate need of foodinfo-icon.

The warring factions must ensure deliveries of food and medical aid to starving people, senior UN officials said at a donor conference in Geneva.

Nearly $1.1 billion has now been pledged towards a United Nations appeal of $2.1 billion for Yemeninfo-icon this year, UN Secretary-General Antonio Guterres announced, calling it a "remarkable success".

"Across Yemen, hunger and malnutrition have reached unprecedented levels and the threat of famine looms large. The country is on the brink of catastrophe," said David Beasley, executive director of the UN's Worldinfo-icon Food Programme.

The government, backed by Saudi Arabiainfo-icon and the West, have been fighting the Houthi movement aligned with Iraninfo-icon for over two years in a warinfo-icon that has killed at least 10,000 people.

A Saudi-led military coalition is preparing an assault on Hodeidah, which lies on the Red Sea and is the point of entry for nearly 80 per cent of Yemen's food imports. "The Hodeidah port is a critical lifeline," Beasley told the conference. "Any disruption to the port would gravely hamper efforts to prevent famine." Yemeni officials said earlier this month the government and its allies had positioned two brigades for a possible attack, one of them 230 km north of Hodeidah and the other 130 km to the south.

But Yemeni Prime Minister Ahmed Obeid Bin Daghr, whose government is based in the southern port of Aden and controls only part of the country, said it would allow access for aid supplies and was "ready to open new corridors for this aid".