Thailand and Cambodia plan to rebuild mutual trust and gradually consolidate a ceasefire after weeks of border clashes, Beijing said in a communique with the two countries following talks in southwestern China.

The Southeast Asian neighbours on Saturday ended weeks of fierce fighting that killed at least 101 people and displaced more than half a million with their second ceasefire since late October.

Thailand and Cambodia's top diplomats travelled to the Chinese province of Yunnan for trilateral talks with Chinese Foreign Minister Wang Yi to discuss the border situation on Sunday and Monday.

In a meeting with his Thai and Cambodian counterparts, Wang called the ceasefire "hard-won," and urged the two nations not to abandon it halfway or allow fighting to resume.

"An important consensus was reached," Wang said, according to a statement released by his ministry.

Thailand and Cambodia will "rebuild political mutual trust, achieve a turnaround in relations, and maintain regional peace," according to a joint communique released by the Chinese ministry.

'STEP BY STEP'

Thailand's foreign ministry said after the talks that it saw "the need to gradually build mutual trust and confidence between the two governments and peoples".

"Thailand reiterated that adjustment on relations should be done on a step by step basis," a statement from the ministry said.

It also said Thailand would "consider the release of 18 soldiers after the 72-hour ceasefire observation period and request that Cambodia facilitate the return of Thais along the border."

Thai and Cambodian defence officials joined the talks in China, with diplomats and defence officials from the two countries holding a number of bilateral meetings.

Cambodian foreign minister Prak Sokhonn told local media after the talks in China that there would be "open communication" between foreign and defence ministers "to rebuild trust".

"We are open communications to avoid small issues from getting bigger, so that the relationship between the militaries can be handled smoothly," he said.

LAND MINES

The latest round of clashes began early this month after a breakdown in a ceasefire that U.S. President Donald Trump and Malaysian Prime Minister Anwar Ibrahim helped broker in July to halt a previous round of fighting.

In a sign of the possible fragility of the ceasefire, the Thai army reported earlier on Monday a landmine incident in the border province of Sisaket. A member of its mine clearance team lost his left leg and injured his left eye, it said.

Landmine incidents had been a catalyst for clashes between Thailand and Cambodia since July.

The Thai army said "evidence of anti-personnel mine deployment consistently shows Cambodian forces continue to use such weapons," calling it "a grave violation of international humanitarian principles and is unacceptable to the global community."

China said it was willing to offer demining support.

A statement from Cambodia's State Secretariat of Border Affairs said a border demarcation meeting would be held during the first week of January in Siem Reap.

The Thai side has not yet confirmed such a meeting.