Pro-government forces and Iran-backed rebels in Yemen began exchanging hundreds of prisoners on Wednesday on day two of UN-brokered talks in Switzerland and as a fragile ceasefire appeared to hold.
Some 375 Huthi rebels and 285 pro-government fighters are expected to be involved in the swap which began "in small groups" according to Mokhtar al-Rabbash, a member of the pro-government prisoners' affairs committee.
The exchange is taking place along the boundary between the southern province of Lahj and the central province of Baida, witnesses said.
"Due to the security situation, we had to divide the prisoners into groups of 20 each," said Rabbash, adding that the detainees were being transferred in buses.
Military sources in the area warned that security threats along the exchange route could slow the process.
The International Committee of the Red Cross in Sanaa, which was involved in a previous prisoner swap, said earlier the organisation was "not aware of such an exchange".
Although the fighting in Yemen has subsided, both sides traded blame for violations that have left at least 24 people dead since the truce began at midday (0900 GMT) on Tuesday.
The Saudi-led coalition supporting embattled President Abedrabbo Mansour Hadi accused the Huthi Shiite rebels of flouting the ceasefire from its very first hours, and acknowledged that it had "responded to these violations".
The rebels, meanwhile, accused the coalition of breaking the truce immediately after it began by carrying out "a series of raids on various provinces".
This mutual animosity underscored the challenge facing delegates at the talks which began in Switzerland on Tuesday.
Previous ceasefires have collapsed, and earlier UN efforts have failed to narrow differences between the warring parties.
The UN envoy to Yemen, Ismail Ould Cheikh Ahmed, has called the truce "a critical first step towards building a lasting peace in the country".
A spokesman for the coalition, Saudi Brigadier General Ahmed al-Assiri, said that the alliance's leadership "realises that this is an important and crucial phase to find a peaceful solution, but has a military commitment to respond to violations".
- Saudi soldier killed -
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The coalition launched an air war against the rebels in March after they forced Hadi to flee the country, and has also sent in ground troops.
On Wednesday, military sources reported mortar and gunfire by rebels in several parts of the besieged provincial capital of Taez.
Pro-Hadi forces also attacked rebel positions in the city, a military source said, and fighting was also reported in Marib province east of the capital.
The coalition also said a Saudi soldier was killed "while protecting the kingdom's borders from aggressing rebels" in the kingdom's southwestern Najran area, SPA state news agency reported.
On Tuesday, just hours after the truce came into effect, rebel artillery and tanks killed seven civilians and wounded 15 in Taez, witnesses and medics said.
Rebels also killed 17 loyalist fighters and wounded 20 in Marib, a military source said.
Hadi has said he wants a seven-day truce to coincide with the peace talks to be "renewed automatically if the other party commits to it", the coalition said.
Little news has emerged from the open-ended talks in Switzerland.
UN spokesman Ahmad Fawzi told reporters on Tuesday that 12 negotiators and six advisers made up each of the two delegations attending the talks.
"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 said.
A ceasefire is much-needed in the Arabian Peninsula's poorest nation, where the UN says an estimated 80 percent of the population requires humanitarian aid.
The World Health Organization representative in Yemen, Ahmed Shadoul, said the agency had received assurances that it was free to distribute medical supplies while the truce holds.
More than 5,800 people have been killed in Yemen -- about half of them civilians -- and more than 27,000 wounded since March, according to the UN.