Once reluctant exchanges are now moving into the crypto space as bitcoin recovers from a crash to hit all-time highs of nearly $74,000 last week, gaining more than 50% this year, as inflows into U.S. listed bitcoin funds surged.

London Stock Exchange Group this month said it plans to accept applications for crypto exchange-traded notes later this year, debt securities that provide professional, but not retail, investors, with exposure to cryptoassets.

Deutsche Boerse in Frankfurt also said this month it had launched a regulated platform for the trading of crypto currencies for institutional investors.

But Boujnah indicated that he was in no rush to join his European rivals as regulators for Euronext, whose largest trading operations are in Italy, France and the Netherlands, remain lukewarm at best towards crypto.

"We always considered this is an issue we cannot engage without absolute backing from supervisors," he told reporters.

"We've always been very cautious about cryptoassets... a little for conceptual reasons and a lot because our regulators themselves are extremely so."

Boujnah added that regulators in Rome and Amsterdam were clearly against it, while France's regulator was very cautious.

"Our regulators don't have the same sense of humour," he quipped.

(Reporting by Mathieu Rosemain, writing by Inti Landauro and Huw Jones, editing by GV De Clercq and Louise Heavens)

By Mathieu Rosemain