Cryptocurrency aficionados have been flocking to Puerto Rico, attracted by a provision that exempts relative newcomers to the island from paying taxes on their capital gains.

But the governor of Puerto Rico is not quite sold on crypto.

"Cryptocurrency is sort of an application of that — I am concerned with some of the reports that have been going on there on how this is being used," Gov. Ricardo Rossello said in an interview with CNBC. "So, in my view, there is still a lot of work to be done and giving clarity that this is not used for money laundering or it's not used for other areas."



Still, he's much more bullish about the prospect of blockchain, something he calls a "phenomenal technology" and a "game changer."

"We would really, at least my administration, would like to take advantage of the blockchain component of it because it has transformative and disruptive components for business and for government," Rossello said.

Puerto Rico is luring crypto entrepreneurs and investors thanks to an exemption within the Internal Revenue Code, called Act 22, that allows nonresidents of Puerto Rico to pay no taxes on their long-term capital gains.

Puerto Rico is calling itself the "friendliest locale in the United States for entrepreneurs, investors and service providers in the crypto-currency and blockchain arena," according to a description of a conference called "Puerto Crypto," which is taking place next month.

The 2½-day conference is partnering with the Puerto Rico Department of Economic Development and the governor's office.

Rossello is slated to speak at the event.