Officials from Yemen’s internationally recognised government on Wednesday said it was hopeful that a prisoner-exchange operation due to take place this week will go smoothly. Yemen’s warring parties agreed to a prisoner swap during 2018 peace talks in Sweden that would allow for the exchange of 15,000 men and women. It was seen as a breakthrough in the war that has caused the world's worst humanitarian crisis. Last month, the two sides again said they would work towards the swift exchange of about 1,000 prisoners. The UN and Red Cross have tried to mediate the implementation of the deal but obstacles have so far delayed major releases. The operation, scheduled for Thursday and Friday, will involve the immediate release of 1,081 conflict-related detainees and prisoners by the Iran-backed Houthi rebels and government. A Yemeni official with close ties to the government’s negotiations team said the dates are yet to be confirmed because some technical issues have arisen. The official was not allowed to specify what the issues were but said the Houthis had presented some obstacles to the swap. “It is known that the Houthis want to create problems and this is something that is not new and we are used to it,” he said. The rebels have approved the release of 400 government prisoners, including 15 Saudi and four Sudanese citizens. The Saudi-backed government will free 681 Houthi fighters, a member of the government delegation said. Since the 2018 agreement, the two sides have made sporadic prisoner swaps but the release of hundreds would mark the first large-scale handover since the war began in 2014. The prisoner-swap deal is part of several confidence-building measures to help pave the way for wider peace talks to end the five-year civil war in Yemen. The confidence-building measures include a ceasefire in the strategic port city of Hodeidah. The halt in fighting, however, stumbled over military actions and distrust between the two sides. The peace efforts gained more international attention as the coronavirus pandemic threatened Yemen's devastated health system. But fighting continued to rage as the rebels pushed into the oil-rich government stronghold of Marib. The war in Yemen 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 to restore President Abdrabu Mansur Hadi's government to power.