The allegations came after three Thai soldiers were injured after they stepped on landmines along the border Tuesday, the Bangkok Post reported.
The Cambodian Ministry of Defense Friday called Thailand's accusations "false and groundless."
Thai officials also denied having planted the landmines.
"We will check who planted the landmines there, but we did not put them there," Army chief Prayuth Chan-ocha said Friday. "Someone else did."
"I ask soldiers along the border to exercise caution and I feel for them because being a soldier means you have to risk your life," Prayuth said.