By Stephanie Nebehay

GENEVA, April 24 (Reuters) - Aid agency Oxfam called on donor nations on Monday to step up life-saving assistance to millions of civilians in Yemen facing starvation and disease, rather than providing arms to fuel the deepening conflict.

"Many areas of Yemen are on the brink of famine, and the cause of such extreme starvation is political," the British charity said on the eve of a United Nations conference in Geneva to seek aid pledges for the Arab country.

Western governments were attending the event "while they continue to sell billions of dollars worth of weapons and military equipment to parties to the conflict," it said.

The food crisis could worsen if the international community does not send a clear message that a coalition attack against Hodeidah, the strategic Red Sea entry point for some 70 per cent of Yemen's food imports, would be "totally unacceptable", Oxfam added.

Alexander Ventura, emergency coordinator and head of mission in Yemen for Medecins Sans Frontieres (MSF), said: "The health system is at the verge of collapse and medical services are under fire."

Yemen is reeling from two years of civil war that pits Houthi rebels, aligned with Iran, against a Western-backed, Saudi-led coalition that is carrying out air strikes almost daily. At least 10,000 people have been killed in the fighting, which has unleashed a humanitarian crisis.

The U.N. has so far only received 15 percent of $2.1 billion sought in aid for Yemen this year.

"Bilateral and institutional donors must prioritise assistance to the country's health system to avoid total collapse," Ventura said, adding that doctors and nurses had not been paid in six months.

Civilians are "deliberately targeted" by all warring sides, he said, and severe acute malnutrition was on the rise.

"Children are more at risk of dying from preventable diseases, pregnant women are unable to deliver safely and people suffering chronic conditions like renal failure are in need of dialysis," he said. "Silent deaths must be prevented."

MSF, which supports 12 hospitals across Yemen, uses Hodeidah and other ports to bring in medical supplies but has begun airlifting goods to Aden, Hodeidah and Sanaa, Ventura said.

"We are keeping an eye on Hodeidah, if (an attack) happens to provide assistance as well. We are getting ourselves prepared, we are already supporting some health facilities."

(Reporting by Stephanie Nebehay; Editing by Mark Trevelyan) ((Stephanie.Nebehay@thomsonreuters.com; +41 58 306 2161; Reuters Messaging: stephanie.nebehay.thomsonreuters.com@reuters.net; twitter @StephNebehay))