KUALA LUMPUR - China on Sunday (Dec 28) welcomed a ceasefire between Cambodia and Thailand after weeks of deadly border clashes, as officials from the three countries prepared to open a two-day meeting in southwestern China.

Chinese Foreign Minister Wang Yi called the ceasefire "an important step towards restoring peace" and said it was "in line with the shared expectations of countries in the region."

Thailand and Cambodia ended weeks of fierce fighting that killed at least 101 people and displaced more than half a million, agreeing on their second ceasefire in recent months.

Cambodia's top diplomat Prak Sokhonn and his Thai counterpart Sihasak Phuangketkeow are expected to meet Wang in Yunnan province on Sunday and Monday to discuss the border situation.

Wang said Cambodia and Thailand should "promote a complete and lasting ceasefire, resume normal exchanges and rebuild mutual trust."

The truce comes with a 72-hour observation period, at the end of which Thailand will repatriate 18 Cambodian soldiers captured in July, a major demand of Cambodia.

China has positioned itself as a mediator in the crisis, alongside the United States and Malaysia, and also announced 20 million yuan of emergency humanitarian aid for Cambodia to assist the displaced.

The first batch of Chinese aid, including food, tents and blankets, arrived in Cambodia on Sunday, Wang Wenbin, Chinese ambassador to Cambodia, wrote on Facebook.

At a Thai university converted into a shelter, some displaced residents are still reluctant to return home despite the ceasefire.

"I really hope this ceasefire will last long and we can return home.

"But I will not go back home as long as authorities do not confirm that it is safe," said 21-year-old homemaker Kanlaya Somjettana from Surin city, noting that the evacuation centre was now less crowded, although hundreds remained.

On the Cambodian side, some evacuees are also cautious, waiting for confirmation that it is safe to return.

"Despite the ceasefire, we dare not return home yet. We are still frightened.

"We will wait to see the situation for a few days, if it will stay calm," said 35-year-old So Choeun, sheltering with family under makeshift tents at a Buddhist pagoda in Banteay Meanchey province.

Officials on both sides said the ceasefire was holding, but for most areas, no all-clear notice had been issued.

The truce follows three weeks of renewed cross-border fighting that killed at least 47 people and displaced more than a million on both sides.

Wang told his Cambodian counterpart Prak Sokhonn that the ceasefire "has opened the process of rebuilding peace."

"In the next step, both sides should proceed step by step to promote a comprehensive and lasting ceasefire, restore normal exchanges, rebuild mutual trust, and achieve a turnaround in relations," he added.

A previous round in the decades-old conflict, five days of fighting in July, killed dozens before a truce was brokered, and then broken.

Many displaced by the latest violence had evacuated in July as well.

Rice and cassava farmer Saichon Wongpitak said she could not wait any longer and planned to return to her home in Thailand's Sisaket province on Sunday afternoon.

"I talked to our neighbour who said there was no gunfire since yesterday.

"We have fear ... but we have jobs to do at home, we have cattle at home, we have our farm," she said.

Saichon said she welcomed the truce but did not expect it to last long "before Cambodia starts a new round of fighting."

"I live on the border and what I have learned is not to trust Cambodia," she added.

Kot Ngik, 43, from another camp in Cambodia's Banteay Meanchey, said the truce may allow children to return to school.

"But we don't trust the Thai military yet.

"At this point, we are not sure about the situation. They can fight again at any time," she said.

While many evacuees were still fearful, So Choeun said the ceasefire offered some hope.

"Yesterday morning, I could hear loud bangs, but I have not heard it since 12pm yesterday.

"This is a good sign," she added.