Cambodian and Thai soldiers on Wednesday exchanged gunfire in a disputed area on the Thai-Cambodian border, leaving five Thais wounded, one Cambodian dead and fanning the flames of a diplomatic row between the two neighbours, military sources said.

In Phnom Penh, it was claimed that Thailand had violated Cambodian airspace twice Wednesday morning.

"The Thai fighter jet came 8:50 am and again at 10.07 am to disturb our airspace. Cambodian soldiers wanted to fight then, but they were placated for a while," the head of Cambodia's Preah Vihear authority, Hang Soth, said in Phnom Penh.

In Bangkok, the Thai Foreign Ministry issued an "aide memoire" to Cambodia, accusing the country of initiating the clash, which lasted five minutes between 2:25 to 2:30 pm, injuring five Thai soldiers.

"Thai soldiers, while peacefully patrolling the area along the Thai-Cambodian border inside Thai territory near Phu Ma Khua, were shot at by Cambodian soldiers using RPG and sub-machine guns, which resulted in the injuries of five Thai soldiers," said the memoire.

It added that Thai soldiers returned fire "exercising their inherent right of self-defence as provided for under Article 51 of the Charter of the United Nations."

"The Royal Thai Government considers the above-mentioned intrusion of the Cambodian soldiers into Thailand's territory as well as the shooting at the Thai soldiers a serious violation of Thailand's sovereignty and territorial integrity as well as the commission of an act of aggression in blatant violation of international law," it added, demanding the immediate withdrawal of Cambodian troops from Thai territory.

The shootout occurred about 3 kilometres away from Phreah Vihear, an 11th century Hindu temple that has been the cause of many border disputes between the two neighbouring countries for almost five decades.

A similar skirmish occurred at the same site on October 3 that left two Thai soldiers and one Cambodian wounded. Thailand issued an official protest to the Cambodian government over the alleged border incursion.

Thai residents along the border have been told to evacuate in case of an escalation in the fighting, according to local media reports.

Thai Foreign Minister Sompong Amornvivat also urged Thai nationals in Cambodia to return to Thailand immediately.

"Thai businessmen who have no need to be in Cambodia now, please rush back to Thailand," Sompong told reporters.

Thailand and Cambodia nearly came to blows over the Preah Vihear temple in July, shortly after UNESCO named the ancient Hindu temple a World Heritage Site despite Thai objections.

The temple, the object of disputed claims between Thailand and Cambodia since the 1950s, was granted to Cambodia by a ruling of the International Court of Justice in 1962.

But land adjacent to the temple compound, including its main entrance on the Thai side, has been claimed by both countries.

Both sides beefed up their troops in the area, situated about 400 kilometres north-east of Bangkok, after some ultra-nationalist Thais crossed into the disputed zone in a protest against the UNESCO ruling.

The border conflict was calmed in August when both sides agreed to settle the matter through bilateral talks held by a joint border committee.

The talks have been hampered by repeated claims of incursions into Cambodian territory and by Thailand's chaotic domestic political situation.