At least 20 foreigners were arrested in Pattaya when police raided an eight-storey hotel that had been converted into a casino centre.

The raid at 11.30pm on Monday was prompted by Pattaya police reports of foreigners gambling in the Antai Holiday Hotel in Bang Lamung district.

Police reported a stream of foreigners entering and leaving the hotel at night. 

The hotel occupies the eight-storey building, with Thai employees working in the reception area on the first floor.

The casino was operating on the second floor, police said. Gambling supplies, including poker cards and chips, were seized. 

The third to seventh floors were still hotel rooms.

Police caught six Chinese nationals working at computers on the top floor. An examination of the equipment revealed they were sending ransomware links to companies in China.

At least 20 foreigners were arrested during the raid, mostly Chinese but also Vietnamese, Singaporean, Cambodian and Myanma, according to police.