The raid followed intelligence that showed a building in Yannawa district operated a Chinese restaurant on the first floor and a poker den on the third floor.
More than 20 gamblers were found on the third floor but 12 of them were arrested – 10 men and two women.
Eight of the arrested gamblers are from China, two from Singapore and one each from the Philippines and India. The police also arrested one Thai who is the building caretaker.
All suspects were taken to Bang Phong Phang Police Station for interrogation.
Police confiscated 319,400 baht, 5,308 Singaporean dollars, 7,035 Chinese yuan, 12,074 Hong Kong dollars, 100 euros and 70 Macanese pataca, as well as two bags of cash chips worth 5.98 million baht, 10 card decks, a poker table, nine chairs, 15 telephones and 45 bottles of illegal imported liquor.
A foreign gambler told the police that he had been invited to the gambling den by his foreign friend, saying that he did not know gambling was illegal in Thailand.
The Thai building caretaker said she had been hired by a Chinese employer for a year.
Initially, police charged the gamblers for playing without permission, and a Thai national for organising the gambling. Investigation is underway to seek more suspects.