Cambodia has shut its border crossings with Thailand, as fighting continues between the two forces on Saturday despite US President Donald Trump earlier saying they had agreed to a ceasefire.

The crossings will be closed until further notice, according to Cambodia's interior ministry.

Earlier, Thai Prime Minister Anutin Charnvirakul said he told Trump a ceasefire would only be possible after Cambodia had withdrawn all its forces and removed landmines.

Thai officials said four soldiers were killed on Saturday, as both sides reported continued bombing and artillery exchanges. Cambodia has not been updating its military casualty figure.

Cambodia's defence ministry stated that Thai fighter jets bombed hotel buildings and a bridge, while Thailand reported several civilians were injured in a Cambodian rocket attack.

The four deaths on Saturday bring Thailand's total military death toll since Monday to 15, with 270 others injured. It added that six civilians had also been injured.

On Friday, Cambodia said at least 11 civilians had been killed and 59 others injured. At least 700,000 people have been evacuated on both sides of the border.

Trump had claimed earlier in the week that he could stop the fighting between Thai and Cambodian forces that broke out on Monday just by picking up the phone.

After speaking to both prime ministers on Friday night, he wrote on social media that the two countries had agreed to cease shooting effective this evening and go back to the agreement they signed in front of the US president in October.

However, in their comments after speaking to the US president, neither side mentioned an imminent ceasefire.

Anutin stated he told Trump that Thailand was not the aggressor and that Cambodia must show proof of its troop withdrawal and landmine removal before a ceasefire could happen. They must show us first, he said.

The Cambodian leadership has insisted that they must fight on to protect their country's sovereignty.

On Saturday, Cambodia reported that it had been struck by further Thai airstrikes.

The Thai military confirmed that fighting continued along their border.

The ongoing border dispute escalated on July 24, when Cambodia launched a barrage of rockets into Thailand, which responded with air strikes. Both sides accused each other of initiating the conflict.

After days of intense fighting leaving dozens dead, both countries agreed to an immediate and unconditional ceasefire brokered by Trump and Malaysian Prime Minister Anwar Ibrahim, formalized in a ceremony presided over by Trump.

However, both sides continue to accuse each other of ceasefire violations. Thailand has reported evidence of Cambodian troops laying landmines which have injured Thai soldiers, while Cambodia attributes the mines to leftover conflicts from the 1980s.

This week, further air strikes were initiated by Thailand after two of its soldiers were injured.

The tensions have been escalating over more than a century, with both countries contesting their 800 km land border first delineated by French cartographers in 1907.