The US has asked Thailand and Cambodia to cease hostilities immediately as border clashes extended for a third day, killing at least 10 people and displacing hundreds of thousands.
The two nations must follow de-escalatory measures outlined in a peace accord brokered by US President Donald Trump in October, Secretary of State Marco Rubio said.
Trump has also said that he would make a phone call to stop the fighting, which is the most serious escalation since clashes in July killed dozens of people.
Both countries have blamed each other for re-igniting the fighting, which has seen air strikes and exchanges of artillery fire.
The death toll over three days of hostilities stands at 10 - seven from Cambodia and three from Thailand. Thai officials said they evacuated more than 400,000 people, while Phnom Penh said 100,000 on the Cambodian side have been moved to shelters.
Thailand's defence ministry stated that military actions were limited in scope and employed as a last option. Peace must come with the safety and security of our citizens, full stop, the ministry's spokesman said.
Cambodia has accused Thailand of launching aggressive military attacks that targeted civilian institutions and sacred cultural sites, including historic temples along the disputed border.
Also on Wednesday, Cambodia announced it was pulling out from the Southeast Asian Games being hosted in Thailand due to serious concerns and requests from the families of its athletes, marking a significant diplomatic stance under the circumstances.
UN Secretary-General António Guterres expressed his concern over the situation, urging both sides to exercise restraint and avoid further escalation. The dispute has already led to significant civilian casualties and infrastructure damage.
The century-old border conflict between Thailand and Cambodia has dramatically escalated over the past months, exacerbated by the territorial sovereignty disputes resulting from historical borders set post-French colonialism.
