UN-sponsored talks on a prisoner exchange deal between Yemen's warring sides have been postponed by a day to Friday, according to a Yemeni government source.

The internationally recognised government and Houthi rebels had been scheduled to meet Thursday in Switzerland to finalise a deal that is expected to see more than 1,400 prisoners freed.

"There are members of the government committee who have yet to arrive, so it was decided that discussions on the prisoner swap be postponed until Friday," the source, who spoke on condition of anonymity, told AFP.

The government, supported by a Saudi-led military coalition, and the Iran-backed Houthis agreed to exchange some 15,000 detainees as part of peace deal brokered by the United Nations in Sweden in 2018.

The two sides have since made sporadic prisoner swaps, but the release of 900 loyalists in exchange for 520 insurgents -- if it materialises -- would mark the first large-scale handover since Yemen's war erupted in 2014.

A source close to Yemen's presidency said Wednesday the talks would "lay out the final touches" after agreement was reached with the International Committee of the Red Cross "on all logistical arrangements".

General Nasser Mansour Hadi, brother of Yemeni President Abedrabbo Mansour Hadi, along with 19 Saudis and other politicians and journalists, would be among those released, he added.

A former senior intelligence official, he has been held by the rebels ever since they overran Sanaa in late 2014.

The Yemen conflict has killed tens of thousands of people, most of them civilians, and sparked what the United Nations calls the world's worst humanitarian crisis.