A New Zealander was drugged and robbed by a ladyboy in Thailand after giving the prostitute his PIN code, according to Thai media.

Bernard John Griffiths, 65, met up with the sticky-fingered ladyboy (a person whose physiology is part male, part female) while strolling in Pattaya's red-light district on December 17, and agreed to join him at a bar, the Pattaya Mail reported.

Finding himself short of cash to pay the bill, Griffiths went to an ATM machine with the ladyboy.

He struggled to withdraw cash because he could not read the Thai language on the machine, and rather than choose "English" from the menu, Griffiths gave his card and PIN code to the ladyboy, who helpfully withdrew 10,000 baht (NZ$373) for him.

The pair then went to the Lucifer Disco where they shared a beer, which Griffiths saw the suspect shaking before giving to him, but drank anyway.

He was told the drink was shaken to clear the foam from the bottle.

Griffiths then passed out in a corner, and woke up 15 minutes later alone and without his wallet, Visa card, a diamond ring worth $8000, a gold necklace worth $3000 and the 10,000 baht cash that was withdrawn using the Visa card before the drugging.

Griffiths went to the police, who arrested 26-year-old Kiettisak or Or-Ae after viewing CCTV footage, the Pattaya Daily News reported.

Kiettisak admitted drugging Griffiths with alprazolam, a sedative drug sold as Xanax, according to the Pattaya Daily News.

Police searched Kiettisak's bag and found a knife and camera that belonged to a 35-year-old Russian man who had reported them stolen December 16.

Pattaya is a beach resort city on the east coast of the Gulf of Thailand, about 100 kilometres southeast of Bangkok.