Yemen’s government and the Houthi rebels have resumed talks in Switzerland on a prisoner exchange that was part of a peace deal reached nearly two years ago.

The exchange of thousands of prisoners was one of a series of confidence-building measures agreed upon in Stockholm that were supposed to lay the groundwork for a political solution to the conflict, now in its sixth year.

Martin Griffiths, the United Nations envoy to Yemen, said delegates from the internationally recognised government sat down in Geneva with the Iran-backed rebels for talks co-chaired by the International Committee of the Red Cross.

Mr Griffiths urged the parties to “release detainees swiftly” and “bring relief to thousands of Yemeni families”.

A deal to trade 15,000 prisoners was considered a breakthrough during 2018 peace talks in Sweden. The negotiations produced a sequence of confidence-building measures, including a ceasefire in the strategic port city of Hodeidah. But ongoing military offensives across the country and deep-seated mutual distrust has repeatedly delayed the exchange.

Occasional releases of dozens of prisoners over the past two years have served as gestures of good faith, stoking hopes the factions would implement what the UN has described as the war’s “first official large-scale” exchange. The two sides committed earlier this year to swap more than 1,400 detainees

The peace efforts gained more international attention as the coronavirus pandemic threatened Yemen's devastated health system. However, fighting continues to rage as the rebels push into the oil-rich government stronghold of Marib.

Yara Khawaja, a spokeswoman for the ICRC in Yemen, said she welcomed the negotiations “for the sake of the families waiting for loved ones to return home”.

“It’s in the hands of the parties to the conflict to bring long-lasting positive change,” she said.

The office of the UN envoy said it was unclear how long the Geneva talks would take.

Yemen’s war erupted in late 2014, when the Iran-backed Houthis seized the capital, Sanaa, and much of the country’s north. A Saudi-led military coalition intervened the following year in an effort to restore President Abdrabu Mansur Hadi's government to power.

A source close to Yemen's presidency told Agence France-Presse that the talks in Switzerland would "lay out the final touches" after agreement was reached with the ICRC "on all logistical arrangements".

The president's brother, Gen Nasser Mansour Hadi, along with 19 Saudis and politicians and journalists, would be among those released, he said.

A former senior intelligence official, the general has been held by the rebels ever since they overran Sanaa.

The war has killed more than 112,000 people, according to The Armed Conflict Location & Event Data Project, and pushed millions to the brink of famine.