Cambodian workers squeezed through a congested border crossing to return home as border tensions escalated with Thailand.

Thousands of Cambodians waited overnight amid heavy rain to cross the Ban Laem checkpoint in Chanthaburi, Thailand.

Authorities said some 20,000 Cambodians crossed back home as the Chanthaburi-Trat Border Defence Command opened the border gate early morning on Sunday.

Footage shows the crowd of travellers lugging their belongings as they trudged back onto Cambodian soil. More were expected to cross over today, July 28.

Cambodian officials also allowed Thai workers to return to their home country through a crossing in the Thai border province of Sa Kaeo.

The Thai military said they carried out screening to check the travellers' backgrounds and criminal records, as some returning Thais were illegal migrant workers.

The escalating military confrontation - the bloodiest in more than a decade - flared in long-disputed border areas as Thailand and Cambodia accused each other of instigating the violence on July 24.

The Thai army claimed the clash began when six armed Cambodian soldiers approached a Thai outpost after a drone was heard near a disputed Khmer temple. Thai troops said they shouted warnings and claimed the Cambodians opened fire first.

However, Cambodia's Defense Ministry accused Thailand of provoking the violence, saying its forces acted in self-defense.

Officials said today at least 35 people have been killed and more than 218,000 displaced on both sides of the border.

US President Donald Trump threatened to pause trade deals with both countries as he urged both sides to end the fighting on Saturday evening.

He said: 'I spoke to both of the prime ministers, and I think by the time I got off, I think they want to settle now.'

Acting Thai Prime Minister Phumtham Wechayachai and Cambodian Prime Minister Hun Manet have reportedly agreed to meet in Malaysia today, July 28, in peace talks facilitated by Malaysian Prime Minister Anwar Ibrahim, chair of the Association of Southeast Asian Nations (ASEAN).