Cryptocurrency exchange FTX is not authorized to provide services to customers in the U.K., according to the country's financial watchdog.

"We believe this firm may be providing financial services or products in the U.K. without our authorization," the Financial Conduct Authority said in an official notice on Friday.

However, an FTX spokesperson told Bloomberg it believes a scammer is impersonating the company. The spokesperson noted that the phone numbers listed by the FCA do not belong to FTX and are associated with a crypto scam. It said FTX is looking into the matter.

Following the publication of this article, Sam Bankman-Friend, the CEO of FTX, also tweeted a scammer is impersonating FTX in the U.K.

The multibillion-dollar crypto trading platform owned by Bankman-Fried has risen to prominence in the last few months, particularly because of its role in attempting to bail out large crypto firms that crashed during the market downturn earlier this year. FTX is now marked as an "unauthorized firm" in the FCA's registry for financial services.

Companies and individuals "offering, promoting or selling financial services or products" in the U.K. have to be authorized by and registered with the FCA, the notice said, adding that FTX was targeting U.K. customers without the required authorization.

Customers engaging with unauthorized firms cannot access the the Financial Ombudsman Service that settles disputes between companies and individuals, the FCA said. It also said that customers are not protected by the Financial Services Compensation Scheme (FSCS), meaning they are "unlikely" to recover their funds if things go wrong.

CoinDesk has reached out to FTX for comment.

Read more: Crypto.com Exchange Registers With UK Financial Regulator

UPDATE (Sept. 19, 14:13 UTC): Added FTX spokesperson's comment via Bloomberg.

UPDATE (Sept. 19, 15:08 UTC): Adds tweet from FTX CEO Sam Bankman-Fried.