Cambodian troops were spotted setting up a firebase atop a tall building near the Ban Klong Luek border crossing and firing towards the Thai side on Monday morning, security sources said.
The sources said the rifle fire, from a building less than a kilometre from the Ban Klong Luek border checkpoint in Aranyaprathet district, Sa Kaeo, prompted Thai troops to step up security.
They added that Cambodian troops fired intermittently from an upper floor of the building.
Meanwhile, security sources said Thai troops had detected that Cambodian villagers had begun evacuating their homes in the Sampeou Loun area in Malai district of Battambang province.
The sources said the evacuation might indicate Cambodian troops were preparing to open fire from the area, which lies opposite Ban Khao Din village in Klong Had district, Sa Kaeo.