Fighting raged Thursday along the border of Cambodia and Thailand, with explosions heard near centuries-old temples ahead of US President Donald Trump's planned phone call to the leaders of both nations.
At least 20 people have been killed in the latest round of border fighting that reignited last week, officials said.
Around 600,000 people, mostly in Thailand, have fled border areas near where jets, tanks and drones have waged battle.
The Southeast Asian nations dispute the colonial-era demarcation of their 800-kilometre (500-mile) frontier, where both sides claim a smattering of historic temples.
This week's clashes are the deadliest since five days of fighting in July killed dozens before a shaky truce was agreed, following intervention by Trump.
The US president said he expected to speak Thursday with the leaders of Thailand and Cambodia to demand a halt to the clashes.
"I found they were two great leaders, two great people, and I've settled it once," Trump told reporters at the White House on Wednesday.
"I think I can get them to stop fighting," he added.
Speaking to journalists on Thursday, Thai Prime Minister Anutin Charnvirakul said there had been "no coordination" yet with Trump.
"But if there's a call from the US president, we definitely will answer the phone," Anutin said.
"This is an issue between two countries. He has good intentions to see peace but we have to explain what the problems are and why it turned out this way," the prime minister added.
- Life 'paused' -
Both sides blame the other for reigniting the conflict, which has expanded to five provinces of both Thailand and Cambodia, according to an AFP tally of official accounts.
In Thailand's northeast on Thursday, hundreds of evacuated families woke inside a university building in Surin city that has been transformed into a shelter.
A few women pounded chilli paste while volunteers stirred big pots of food.
Nearby, 61-year-old farmer Rat, who declined to give her last name, said she had to leave her home before she could plant a cassava crop this season, fleeing with her family of eight.
"I just want to go home and farm again," she told AFP.
"Every time the fighting starts, it feels like life gets paused all over again."
Nine Thai soldiers have been killed this week and more than 120 wounded, Thai defence ministry spokesperson Surasant Kongsiri told reporters on Thursday, saying that "the operation is still ongoing across the border".
Cambodia's defence ministry has reported 11 civilian deaths and dozens wounded.
Under a makeshift tent on the grounds of a pagoda in northern Cambodia's Srei Snam, 88-year-old Chae Yeang said she wanted her peace of mind back.
"I don't want this war to continue," she told AFP, after having evacuated from her home closer to the border.
"I just want it to end and to have peace tomorrow."
- Outgunned -
AFP journalists in Cambodia's northwestern Oddar Meanchey province heard blasts of incoming artillery from the direction of disputed temples from dawn.
Cambodia's defence ministry said in a statement that Thai forces initiated an attack early Thursday in the province, "shelling into Khnar Temple area".
Cambodia is vastly outgunned and outspent by Thailand, according to available data on military hardware and expenditures.
And the Thai military has hundreds more jets, armoured fighting vehicles and other heavy armaments in its inventory, compared to the forces of its smaller neighbour, data from the International Institute for Strategic Studies showed.
Cambodia's defence ministry said more than 192,000 people have been evacuated, while in Thailand, authorities said more than 400,000 civilians have taken shelter elsewhere.
The United States, China and Malaysia, as chair of the regional bloc ASEAN, brokered a ceasefire back in July.
In October, Trump backed a follow-on joint declaration, touting trade deals with Thailand and Cambodia after they agreed to prolong their truce.
But Thailand suspended the agreement the following month, after Thai soldiers were wounded by landmines at the border.
- Disputed temples -
The United Nations cultural agency called Wednesday for "protection of the region's cultural heritage in all its forms".
In 2008, military clashes between Thailand and Cambodia erupted over a patch of land next to the 900-year-old temple, located on the border.
In the current hostilities, Cambodia also reported damage at another contested border temple, Ta Krabey, which Thailand calls Ta Khwai.
By Chayanit Itthipongmaetee With Suy Se In Oddar Meanchey, Cambodia And Thanaporn Promyamyai In Bangkok