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A woman touches an ATM machine for digital currency Bitcoin in Hong Kong on December 18, 2017.
Friction is increasing between some credit card companies and customers who want to use the cards to buy cryptocurrencies.
Bank of America and Citigroup are reviewing policies that allow customers to buy bitcoin with credit cards. The reviews follow news about two weeks ago that Capital One Financial has decided to prohibit cryptocurrency purchases.
Toronto-Dominion Bank subsidiary TD Bank also confirmed to CNBC that some bitcoin transactions aren't being processed as the result of security measures.
The Wall Street Journal first reported news of Bank of America's cryptocurrency review Thursday. Discover Financial Services effectively prohibited cryptocurrency purchases with its credit cards in 2015, the Journal said. Discover did not immediately respond to a CNBC request for comment.
Money laundering appears to be a factor in the financial firms' concerns about dealing with cryptocurrencies. Discover CEO David Nelms said in a Bloomberg report Wednesday that financing purchases of cryptocurrencies creates headaches for banks that are required to monitor transactions for money laundering.
Earlier this month, Visa also ended its relationship with cryptocurrency card company WaveCrest, which allows people to convert their cryptocurrencies into cash loaded onto a prepaid card.
Jamie Dimon's J.P. Morgan Chase is still allowing customers to buy cryptocurrencies with their Chase credit cards, the bank told CNBC. However, Chase did not respond to a question about potential changes to that policy.
— CNBC's Annie Nova contributed to this report.