Mr Naris confirmed a claim by the owner of Panan Jewelry shop that the coins are rare.
Punnawat Siriruengwanich, in a posting on social media, offered 100,000 baht for one of the 10-baht coins issued in B.E. 2533 (1990).
The Panan Jewellrey shop owner said the 10-baht coins were exceedingly rare as only 30 of the 100 coins issued in that year returned to Thailand from the exhibition.
News of the offer made media headlines during the weekend.
Mr Naris said he had checked with deputy director-general of the Treasury Department at the time and received confirmation that only 100 of the 10-baht coins were issued in B.E. 2533.
The coins were distributed to people attending a mint exhibition in England in that year as a public relations excecise, to let them know that Thailand would cease issuing 10-baht banknotes and replace them with 10-baht coins.
"I believe the 2533 10-baht coins are rare in Thailand. Most of the issue might be in the hands of foreign coin collectors. I am not sure if the department still has any of them," he said.
Mr Naris said according to the department's records, the treasury in B.E. 2532 (1989) ordered 100 million blank coins from the Italian State Mint.
In the following years, the department ordered another 50 million blank coins from an American company, Olin Brass.
The blank coins ordered in 1989 and 1990 were part of the Treasury Department's preparations to issue 10-baht coins and cease issuing 10-baht banknotes, Mr Naris said.