The distraught wife of a Thai soldier missing in action is praying he is alive amid raging border clashes with Cambodia.

Thanyarat Khlangprakhon, 39, said she is still clinging to the desperate hope that her spouse of 13 years would return safe from the war-torn frontier in Surin province.

Sergeant Major First Class Samroeng Khlangprakhon, 38, was one of two Thai soldiers feared killed in fierce skirmishes with Cambodian forces at the recently captured Prasat Ta Kwai temple on December 16.

Authorities said his body has not yet been recovered.

Fighting back tears, the emotional wife said she continues to pray that the father of her four children somehow survived.

She told reporters it was Samroeng's lifelong dream to fight on the frontlines, and that he had 'wanted to die on the battlefield'.

She added: 'I never tried to stop him because he was very serious and loved his job. I have to accept that my husband has achieved what he had wanted.

'Even though I've been told that his body has not yet been found, I am still hoping for a miracle, that he is still alive on the battlefield and they just haven't found him yet.'

The sergeant's older sister, Chongkho Klangprakon, 48, said her brother had disappeared while soldiers were pulling out injured troops from the battlefront.

She said: 'I think it might be because many Cambodian soldiers had arrived, or maybe they did something to his body. I just hope that his body will be found and brought back so we can give him the proper traditional funeral rites.'

The Royal Thai Army said on Wednesday that it has launched an urgent mission to search for two missing soldiers believed to have been killed in an overnight clash along the border.

The two men, Samroeng and Private Phanuphat Saosa, reportedly vanished when Thai troops met heavy Cambodian resistance.

An immediate search could not be carried out due to hostile conditions, officials said.

The 2nd Army Region expressed condolences in a statement, adding Thai forces have secured the temple grounds and surrounding areas at Prasat Ta Kwai.

Territorial clashes flared up earlier this year before a brief ceasefire, but started again this month when Cambodian troops are said to have fired on a Thai engineering team building an access road in a disputed border area.

In the most recent battles, at least 21 Thai soldiers and one civilian have been killed.

In Cambodia, the number of military fatalities is believed to be much higher, though regime chiefs have not revealed the actual figure.

Around 600,000 people have been displaced on both sides of the border.

Cambodia's assault has largely been wayward, unguided rockets fired indiscriminately into Thai territory, including an attack on July 24 that killed eight people and injured 13 others. Thailand has used precision drone strikes and fighter jet strikes on military sites.

Former Khmer Rouge henchman and Cambodian dictator Hun Sen has repeatedly claimed that he wants peace and that Thailand is the aggressor.

Thai officials claim the ongoing border confrontations are a threat to national security, and the areas must be secured.