Thirty aid agencies working in war-torn Yemen on Monday called on rival forces to extend a four-month long truce helping millions of struggling civilians, one day before it expires.

Yemen's conflict, pitting the Saudi-backed government against Iran-backed Huthi rebels, has killed hundreds of thousands directly or indirectly and pushed the country to the brink of famine.

A UN-brokered truce that took effect in early April has provided a rare respite from violence for much of the country and alleviated some of the suffering.

"During the past four months, ordinary Yemenis have experienced the longest period of calm in the country in over seven years," the aid groups said in a joint statement.

"Since the truce entered into force on April 2, reports of civilian casualties have dropped significantly."

The aid groups, including Yemeni and international organisations, urged "all parties to the conflict to adhere to and extend the agreement to protect civilians across the country".

International signatories included ACTED, Action Against Hunger, the International Rescue Committee, Islamic Relief, Oxfam and Save the Children.

The truce, initially agreed for two months, was extended again on June 2 for the same period.

Under the truce, commercial flights have resumed from the rebel-held capital Sanaa to Jordan and Egypt, while oil tankers have been able to dock in the lifeline port of Hodeida, also in Huthi hands.

"An extension of the truce, adhered to by all parties, would support further fuel shipments into the country, allow more people to benefit from commercial flights from Sanaa, and support humanitarian actors to reach those most in need," the groups said.

"Most importantly, it would protect the lives of ordinary Yemenis and open the door to longer-term peace", they added.

sy/mah/aem/pjm/lg