Yemen's warring sides sat down for peace talks in Switzerland on Tuesday in a bid to end the devastating conflict as a ceasefire began on the ground, the United Nations said.

"The UN-sponsored consultations aimed at finding a durable settlement to the Yemen crisis started today in Switzerland," UN spokesman Ahmad Fawzi told reporters.

"These consultations seek to establish a permanent and comprehensive ceasefire, secure improvements to the humanitarian situation and a return to a peaceful and orderly political transition," he added.

Yemen's more-than-year-long conflict has pitted local forces backed by a Saudi-led coalition fighting in support of President Abedrabbo Mansour Hadi's government against Shiite Huthis and renegade troops still loyal to wealthy ex-president Ali Abdullah Saleh.

Previous UN efforts have failed to narrow differences, and past ceasefires were broken.

Fawzi said 12 negotiators and six advisers made up each of the two delegations taking part in the talks, being held at an undisclosed location in Switzerland.

The meeting in Switzerland began after the Saudi-led coalition battling the Iran-backed rebels said a planned seven-day ceasefire had begun.

In May, a five-day pause in fighting proposed by Saudi Arabia allowed some aid into Yemen before the coalition resumed air strikes, blaming ceasefire violations by the rebels.

In a statement, UN Special Envoy on the Yemen crisis Ismail Ould Cheikh Ahmed voiced optimism that the new ceasefire would hold.

"The cessation of hostilities which was called today should mark the end of military violence in Yemen and the transition to progress based on negotiations dialogue and consensus," he said.

"Making peace is a fundamental requirement to rebuild Yemen, rehabilitate the basic infrastructure, address the consequences of the war, provide the necessary environment to normalise life in all governorates, and resume economic activity," he added.

The UN said its experts were working with the delegations "to provide support to develop agreements which improve humanitarian access and delivery and to aid in the development of a comprehensive and permanent ceasefire."

The United Nations says more than 5,800 people have been killed, about half of them civilians, and more than 27,000 wounded since Saudi Arabia launched airstrikes against the rebels in March.