Each side has blamed the other for instigating the fresh fighting and traded accusations of attacks on civilians, after five days of clashes in July killed dozens.
The United States, China and Malaysia brokered a truce to end that round of fighting, but the ceasefire was short-lived.
Border temple clashes
In October, US President Donald Trump backed a follow-on joint declaration between Thailand and Cambodia, touting new trade deals after they agreed in Kuala Lumpur to prolong their truce.
But Thailand suspended the agreement the following month, after Thai soldiers were wounded by landmines while on patrol at the border.
Bangkok has accused Cambodia of laying fresh mines, an allegation denied by Phnom Penh.
Trump, who has placed the conflict between Cambodia and Thailand on a list of wars he said he solved, this month claimed the two countries had agreed to a new ceasefire.
But Bangkok denied any truce had been agreed, and fighting has continued daily since a border skirmish on December 7 sparked the latest clashes.
US Secretary of State Marco Rubio said on Friday that Washington was hoping Cambodia and Thailand would reach a new ceasefire by Monday or Tuesday.
Foreign ministers of Asean nations, including Cambodia and Thailand, are set to meet on Monday in Kuala Lumpur for talks aimed at finding a diplomatic solution.
China sent its special envoy for Asian affairs to Cambodia and Thailand last week, with Beijing aiming to “rebuild peace”.
Cambodia’s foreign ministry said on Saturday that the Chinese envoy, Deng Xijun, met with Prime Minister Hun Manet in Phnom Penh the day before, urging a truce.
Cambodia, which is outgunned and outspent by Bangkok’s military, said on Sunday that Thai forces had continued to attack since dawn, with fighting occurring on the border near the 900-year-old Preah Vihear temple.
A patch of contested land next to the Unesco-listed heritage site was the site of military clashes in 2008, and sporadic violence for several years after led to the deaths of two dozen people.
A UN court ruling in Phnom Penh’s favour in 2013 settled the matter for more than a decade, but this year’s crisis erupted in May when a Cambodian soldier was killed in a new clash.
– Agence France-Presse