Cryptocurrency exchange FTX on Monday said a "scammer" is to blame for the warning it received from the United Kingdom's top financial regulator last week.

On Friday, the Financial Conduct Authority (FCA) said FTX was offering financial services and products in the UK without authorization.

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"Almost all firms and individuals offering, promoting or selling financial services or products in the UK have to be authorized or registered by us," the FCA said in a statement, which also included a link FTX's site and three phone numbers.

In response, FTX CEO Sam Bankman-Fried said in a tweet Monday the exchange was being impersonated by a scammer.

"We're looking into it and communicating with regulators; we believe that a scammer is impersonating FTX," a spokesperson from the exchange told the Wall Street Journal.

The FCA also said that consumers that deal with unauthorized firms will not be covered by the Financial Ombudsman Service or Financial Services Compensation Scheme, programs meant to protect consumers from financial deception.

The FCA said it has issued warnings against about 50 unauthorized and clone firms in the last two weeks. In June 2021, the regulator issued a similar warning against Binance, then the world's largest cryptocurrency exchange.

Earlier this year, FTX began trading on the U.S.-based Nasdaq exchange.

The FCA and regulators across Europe have been considering ways to standardize the crypto industry. In June, the U.K. regulator said that global rules are needed to regulate international crypto firms and "keep markets clean."