Mark Mobius is sensing danger in the explosive growth of cryptocurrencies.

Governments will begin clamping down on digital currencies because of their use in illicit financing, with terrorist groups to drug dealers contributing to their rise, Mobius, executive chairman at Templeton Emerging Markets Group, said in an interview in Hong Kong Monday.

“Cryptocurrencies are beginning to get out of control and it’s going to attract the attention of governments around the world,” Mobius said. “You’re going to get a reversion back to gold because people are going to wonder, can I really trust these currencies?”