At the end of January, the rebels released a captured Saudi soldier while Riyadh set free seven Houthi prisoners, but they are the only detainees exchanged under the deal so far.
UN envoy to Yemen Martin Griffiths said Tuesday at the opening of this round of talks he hoped the two sides would manage to finalize the swap deal.
"Success in this regard is not only of huge importance for those who will be released and return to their families but also to the broader political process in which we are engaged," he said
The prisoner exchange was one of the key breakthroughs at the UN-mediated talks in December.
There are fears that if the exchange fails it could have a knock-on effect on the other key elements – fragile truce agreements for the lifeline port of Hodeida and battleground third city of Taez.
Those deals too have faced problems – while the ceasefires have largely held, timetables for the pullback of combatants have fallen far behind schedule.
Yemen's government and Houthi rebels have agreed on a preliminary compromise for redeploying their forces from the port city of Hodeida, the UN said Thursday.
The conflict in Yemen has killed some 10,000 people since a 2015 Saudi-led intervention and pushed 14 million to the brink of famine, according to the United Nations.
(Cover: United Nations Special Envoy to Yemen Martin Griffiths (C-R) and International Committee of the Red Cross President Peter Maurer (C-L) attend the talks between Yemen's warring parties on prisoners swap, in Amman, Jordan, February 5, 2019. /VCG Photo)