The United Nations calledMonday on all parties involved in the conflict in Yemen to "seize the opportunity" for a diplomatic solution as world powers held virtual talks.

UN Special Envoy for Yemen Martin Griffiths told reporters in Berlin ahead of the negotiations that peace efforts had reached a "critical moment" after six years of fighting.

"This is a moment for responsible leadership," he said, urging "the parties to seize the opportunity that exists now and negotiate in good faith without preconditions".

He was in Berlin at the invitation of German Foreign Minister Heiko Maas.

The meeting brings together high-ranking officials from the five permanent members of the UN Security Council plus Germany, Sweden, Kuwait, and the EU, a format established in 2019 for the Yemen conflict.

Griffiths said the dire humanitarian situation required an immediate response.

"In these six years Yemenis have increasingly and appallingly, lacked access to food and medicine" as well as basic services and freedom of movement, he said.

Children had faced over six years "of being deprived of schooling, and being deprived of their future".

"A generation has been lost," he said.

Griffiths said a UN plan for a negotiated political settlement would first address "critical humanitarian needs and build confidence between the parties".

"We hope together that an agreement on all those humanitarian measures will create a conducive environment for the parties to move swiftly to inclusive peace talks under the auspices of the UN to sustainably and comprehensively end the conflict," he said.

The UN was committed to a "fair future" for the country's people which "is deliverable, which is achievable, and which is long overdue", Griffiths said.

Since the current conflict erupted in 2014 when a Saudi-led military intervention pushed Yemen into a protracted war of attrition, Iran-backed rebels have seized large swathes of the country.

The conflict has killed tens of thousands of people and pushed millions to the brink of famine, in what the United Nations has described as the world's worst humanitarian crisis.