Nine civilians were reportedly killed as Thai and Cambodian soldiers clashed along the disputed border areas this morning.

The residents were caught in a blast after an artillery attack hit a 7-Eleven convenience store at a PTT petrol station in Si Sa Ket, Thailand, on July 24.

Authorities said at least nine people, including two children Bandit Aunjit and Namkhong Boontang aged seven and eight, were killed in the crossfire.

Thailand said it had scrambled F-16 fighter jets to the area, where a stretch of disputed land - handed to Cambodia by the International Court of Justice in the 1960s - has been occupied by Thailand for decades.

Police in the Kanthalarak district said in a statement: 'Due to the BM21 rocket incident, there were initially eight deaths at five locations. Police, military, local government officials, firefighters, local administrative organisations, and medical units are on duty informing civilians to stay away from the area.'

Locals in Kantharalak said they heard gunfire as the clash erupted at 9 am. The skirmish continued for more than two hours as officials evacuated more than 40,000 people from the area.

Both the Cambodian and Thai sides have accused each other of opening fire first.

The Royal Thai Army reported that Thai military officers at Prasat Ta Muen temple in Surin, heard the sound of an unmanned aerial vehicle at 7:35 am but could not pinpoint its location.

Six armed Cambodian soldiers, including one with an RPG, then approached the barbed wire area in front of the Thai base, prompting Thai soldiers to shout at them to stop.

At 8:20 am, the Cambodian side reportedly fired in the opposite direction of the base to the east of the castle before artillery fire was launched around 9 am.

Jirayu Huangsap, spokesman for the Prime Minister's Office, said the government received military information and 'clear evidence' that the Cambodian side initiated the attack.

However, Cambodian PM Hun Manet said Thailand initiated the attack this morning, forcing him to retaliate.

Cambodian troops reportedly fired continuous artillery rounds using 122mm rockets from BM-21 rocket launchers at residents in Surin, where one civilian was killed and a five-year-old child and his family were severely injured. Seven soldiers were also injured in the rocket strike.

The Thai army closed all border checkpoints at 8 am, while the Ministry of Foreign Affairs was instructed to compile evidence of the alleged provocations from the Cambodian side to lodge a formal complaint with international organisations.

The Royal Thai Embassy in Phnom Penh has advised Thai residents in Cambodia to leave as soon as possible. It also urged the public to avoid non-essential travel to Cambodia until the situation is resolved.

The Cambodian Ministry of National Defence condemned Thailand for alleged encroachment.

Prime Minister Hun Manet said Cambodia 'had no choice' but to respond with its armed forces against 'armed aggression'.

The clash flared several days after a border landmine exploded, injuring three Thai soldiers, including one who lost a leg.

Tensions between Thailand and Cambodia escalated after a clash between troops from both countries in a disputed area in Nam Yuen district, Ubon Ratchathani, on May 28, resulting in the death of a Cambodian sergeant.

Thailand expressed its intention to resolve the dispute through existing bilateral mechanisms. However, Cambodia vowed to take the case before the International Court of Justice in The Hague.

Thailand and Cambodia have a fractious history. The Khmer Empire, a precursor to modern-day Cambodia, once stretched across much of Southeast Asia before the ancient leaders moved their base south to Phnom Penh in the 16th century amid water shortages. The abandoned land was then taken over by the Siamese kingdom.