Bipartisan momentum is growing in the Senate and House of Representatives for action to address the risks posed by virtual currencies to investors and the financial system, they said.

Even free-market Republican conservatives, normally wary of government red tape, said regulation could be needed if cryptocurrencies threaten the U.S. economy.

"There's no question about the fact that there is a need for a regulatory framework," said Republican Senator Mike Rounds, a Senate Banking Committee member.

Digital assets currently fall into a jurisdictional gray area between the Securities and Exchange Commission (SEC), the Commodity Futures Trading Commission (CFTC), the Treasury Department, the Federal Reserve and individual states.