PHNOM PENH -- Cambodia's State Secretariat of Civil Aviation (SSCA) on Saturday prohibited all flights from flying across fighting zones with Thailand, a spokesperson said.

Sinn Chanserey Vutha, who is also the SSCA's secretary of state, said all airlines had been informed to avoid flying over conflict zones and the scope of prohibition had been expanded to Poipet City, Pailin province and part of Siem Reap province.

"All flights have been instructed to avoid flying over these airspaces, and the planes must not fly lower than 1,200 meters above sea level," he said in an audio message released to the media.

Vutha said the measures were to ensure flight operations and the safety of the planes and passengers.

He added that as of 10 am local time on July 26, international flights from Phnom Penh to Bangkok and Siem Reap to Bangkok are operating as usual, as planes altered their routes to avoid prohibited airspaces.

Armed clashes between Cambodian and Thai soldiers in border areas broke out on Thursday in Cambodian provinces of Oddar Meanchey and Preah Vihear, and spread to Pursat province on Saturday morning, Cambodian Defense Ministry's Undersecretary of State and Spokesperson, Lieutenant General Maly Socheata, said in a press briefing. According to Thai media, the border clashes started for the third day on Saturday morning after the Cambodian side opened fire against Thai troops.