Fighting was ongoing in at least six areas along the border, Thai Defence Ministry spokesperson Surasant Kongsiri said, and Thai villagers could be seen on video fleeing their homes to seek shelter as the clashes began in the morning.

Following a review of the situation, Smartraveller warned Australians to reconsider their need to travel to the Cambodian border provinces of Preah Vihear and Oddar Meanchey, and the neighbouring Thai provinces of Buriram, Si Saket, Surin and Ubon Ratchathani.

The Cambodian provinces are just north of Siem Reap, a historic city globally famous for stunning temples such as Angkor Wat.

The warnings don’t extend to Siem Reap province itself but do cover several famous temples such as Preah Vihear, Ta Krabei and Ta Moan.

“Armed conflict between Thai and Cambodian military forces along the Thai-Cambodian border has increased,” Smartraveller warned.

“This includes reports of military strikes, violence and the use of landmines in the border areas.

“Follow the advice of local authorities, monitor local media for updates and pay close attention to your personal security.”

Thailand sealed all land border crossings while urging its citizens to leave Cambodia.

A mine explosion along the border on Wednesday that wounded five Thai soldiers triggered the clashes and led Bangkok to withdraw its ambassador to Cambodia and expel Cambodia’s representative.

Longstanding disputes periodically flare along the 800-kilometre border.

They usually result in brief confrontations that sometimes involves exchanges of gunfire but relations have deteriorated sharply since a confrontation in May that killed a Cambodian soldier.

Yesterday’s clashes were far bigger in scale and intensity than usual.

– Reported with Associated Press