Agriculture authorities have vowed to take action against milk producers who have exported school milk to Cambodia, insisting the product is banned for sale in or outside Thailand.
The milk is meant to be produced only for free distribution to local schools.
The Milk Board, also known as the national committee on dairy cows and milk products, will impose a penalty by cutting their quota for supplying milk to the school milk project, Agriculture and Cooperatives Minister Gen Chatchai Sarikulya said yesterday.
He has set up a panel to look into the issue after the Chumchon Khon Thongthin (Local People Community) Facebook page last Thursday cited a complaint by a Thai individual in Cambodia who reported the cartons of milk were being sold at a supermarket in Siem Reap province.
They were priced at US 50 cents (about 18 baht) apiece although the words "not for sale" were clearly labelled on the side of each carton, according to an initial investigation.
The exported milk was later identified as a product of Wang Nam Yen dairy cow cooperatives in Sa Kaeo where chairman Amnuai Thaikok admitted his group sold them in Cambodia but did not think they had broken any law in doing so.
The milk, produced in October last year, was a "surplus amount" after a cut in the group's milk production quota, he said. Selling it was necessary to prevent damage to the business, he added.
"We could not provide the milk to students," Mr Amnuai said, adding: "What was I to do? We had to sell the supply before the milk expired."
The cooperative decided to sell up to 1.1 million cartons of milk in Cambodia, he said, insisting he did not violate the contract because he did not sell them domestically.
However, agriculture permanent secretary Theerapat Prayurasiddhi argued the school milk could not be sold regardless of the circumstances.
The violators will have their quota cut by 5%, he said.
The penalty looks set to lead to further conflict as Mr Amnuai said if his group's quota is reduced, he will file an appeal with a higher authority.