GENEVA - United Nations and Russian officials on Tuesday warned against an attack by Saudi-led coalition forces on the rebel-held Yemeni port of Hodeidah, the aid lifeline for a country where millions of people are in desperate need of food.

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

"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 World Food Programme.

The government, backed by Saudi Arabia and the West, have been fighting Houthi rebels aligned with Iran for more than two years in a war that has killed at least 10,000 people.

A Saudi-led military coalition is preparing an assault on Houthi-held Hodeidah, which lies on the Red Sea and is the point of entry for nearly 80 percent of Yemen's food imports.

"The Hodeidah port is a critical lifeline," Beasley told the UN-organised 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 230 km (140 miles) north of Hodeidah and the other 130 km (80 miles) to the south. Air strikes by the Saudi-led coalition have hampered humanitarian operations to import food and fuel supplies, the United Nations says. Five cranes at the port have been destroyed, forcing dozens of ships to wait offshore for their turn to dock. UN Emergency Relief Coordinator Stephen O'Brien told Reuters on Monday the port had only one operational crane to offload cargo following previous attacks.

The coalition has accused the Houthis of using the port to smuggle weapons and has tried to block ships from entering. Russian Deputy Foreign Minister Gennady Gatilov told the conference that Russia could not accept what he called a blockade. "There are also worrying rumours about an assault on Hodeidah and then a move to on Sanaa, this is something we cannot allow to happen," he said. Gatilov called for a resumption of U.N-sponsored peace talks, which have been stalled for months. "While war is still raging in Yemen, the only winner here will be ISIS, al-Qaeda in the Arab Peninsula and other terrorists and extremists, under whose control whole territories have fallen," he said.

 UN Secretary General Antonio Guterres said nearly 19 million people, or two-thirds of Yemen's population, needed emergency aid. One child under the age of five dies of preventable causes every 10 minutes, he said.

He renewed a call for peace talks and urged all parties to allow the unimpeded passage of humanitarian aid by air, sea and land. "All infrastructure must remain open and operational," he said. Yemeni Prime Minister Ahmed Obeid Bin Daghr said his Aden-based government, which controls only part of the country, would allow access for aid supplies. "We are ready to open new corridors for this aid," he said.

A UN appeal for $2.1 billion for Yemen is only 15 percent covered, Guterres said at the conference opening.

Initial pledges announced at the conference included $150 million from Saudi Arabia, $100 million from Kuwait, $94 million from the United States, and 116 million euros from the European Commission.

The World Food Programme said it reached five million people last month with rations but said it needs to scale up deliveries to reach 9 million deemed "severely food insecure".