Thailand released 18 Cambodian soldiers on Wednesday under an renewed ceasefire agreed by the two countries at the weekend, authorities from both countries said, easing tensions after weeks of deadly border clashes.

The Southeast Asian neighbours agreed to halt fighting at noon on Saturday (0500 GMT), ending about 20 days of clashes that killed at least 101 people and displaced more than half a million civilians on both sides. The fighting included fighter jet sorties, exchanges of rocket fire and artillery barrages.

Cambodian Defence Ministry spokesperson Maly Socheata said the soldiers were transferred at a border checkpoint at 10 am (0300 GMT) on Wednesday, after 155 days in Thai custody. The governor of Cambodia's Battambang province, Sok Lou, described the returnees as "heroic soldiers".

Thailand's Foreign Ministry said the detainees had been treated "in accordance with international humanitarian law and principles" during their detention.

The border clashes flared up again this month after a previous ceasefire deal brokered by US President Donald Trump and Malaysian Prime Minister Anwar Ibrahim collapsed.

As part of Saturday's deal to halt the fighting, Thailand agreed to release the 18 soldiers in its custody if the ceasefire held for 72 hours.

However, the handover was delayed by one day after Thailand made allegations of ceasefire violations by Cambodia, which Cambodia denied.

"Today's release and repatriation of prisoners of war allows families to be reunited and marks an important step in translating the commitments outlined in the Joint Statement into action," said Mirjana Spoljaric, president of the International Committee of the Red Cross, which supervised the handover.