Payments processors Worldpay and Visa said Friday they are reversing duplicate transactions that recently caused unauthorized withdrawals for some users of cryptocurrency exchange Coinbase.
"Worldpay and Coinbase have been working with Visa and Visa issuing banks to ensure that duplicate transactions have been reversed and appropriate credits have been posted to cardholder accounts," the two payments processors said in a joint statement published Friday evening New York time on Coinbase's Medium blog."This issue was not caused by Coinbase."
The statement added that all reversal transactions should appear on customers' accounts in the next few days, and that the majority should already have posted.
Visa and Worldpay confirmed the statement to CNBC. Worldpay works with Coinbase to use Visa's network. Not all card issuers were affected by the issue of unauthorized transactions.
San Francisco-based company Coinbase is the leading U.S. marketplace for buying and selling major cryptocurrencies.
In the last few days, an increasing number of Coinbase users took to Reddit and other social media to complain about duplicate transaction charges that sometimes drained the bank account to zero, with overdraft fees.
The U.S. Commodity Futures Trading Commission said in a statement to CNBC Friday that "the CFTC is aware of customer complaints and is looking into this issue."
The Consumer Financial Protection Bureau also said in a statement that, "We are aware of the reports, and expect companies to comply with all applicable laws regarding the treatment of consumers' funds. Consumers who find unauthorized charges in their bank account or credit card should contact their financial institution immediately."
J.P. Morgan Chase did not respond to a CNBC request for comment. But the bank's support Twitter account said earlier this month, in a reply to a customer who complained about a "$5 non chase atm fee," that:
"The recent change to the way Coinbase transactions are processed is due to a reclassification between the merchant and Visa. Any cash-like transaction, such as this, will be assessed the cash advance fee. This is typically $5 or 5% of the charge."
Wells Fargo declined to comment for this story.
Bitcoin marketplace Coinmama, which also supports Visa, told CNBC Friday they have had no issues so far with payments on their platform.
The impact of the issue Coinbase users were seeing appeared limited. CNBC reached out to more than 30 states where Coinbase is licensed to operate. Of the eight that responded, none of them reported an uptick in complaints against Coinbase.
A spokesperson for the Alabama Securities Commission did point out that typically, complaints can take weeks to arrive at their office. Customers generally first contact merchants, before regulators become involved.