The cabinet has approved a Royal Thai Navy plan to buy a submarine from China, a Defence Ministry spokesman said on Monday.
The approval was made during a cabinet meeting last Tuesday but was not publicly announced.
It involves the purchase of one Yuan Class submarine with the price tag of 13.5 billion baht with the budget earmarked for fiscal 2017-23, Maj Gen Kongcheep Tantrawanit said.
The navy aims to equip the naval fleet with three subs in 11 years, with the total price of 36 billion baht. They will be deployed in the Gulf of Thailand and the Andaman Sea.
The submarine approval was not published in the cabinet meeting minutes, normally published and posted on the government website after weekly meetings.
Maj Gen Kongcheep said the item was not on the meeting agenda.
"[The Defence Ministry] has no intention to hide the issue. It simply was not on the meeting agenda," he said.
"There are many decisions made by the cabinet that need not be announced," the spokesman added.
Government spokesman Lt Gen Sansern Kaewkumnerd, who normally briefs reporters after cabinet meetings, told a different story when asked about the purchase.
"The issue was not included in the briefing because the document was classified as top secret," Matichon Online quoted him as saying.