The Financial Conduct Authority (FCA) has warned about an unauthorised business it says is impersonating a genuine authorised firm.
In a statement the regulator said Anton Falk Capital Partners is an unauthorised clone of a legitimate firm, Anton Falk, which is a regulated firm based in Austria.
The FCA said: "Be aware that the scammers may give out other false details or mix these with some correct details of the registered firm."
The regulator said fraudsters often use the details of a genuine firm to cold call people.
The FCA also warned about the activities of a firm called Options Tec Limited, which it believed to be providing financial services products in the UK without authorisation.
In a statement the regulator said: "This firm is not authorised by us and is targeting people in the UK. Based upon information we hold, we believe it is carrying on regulated activities which require authorisation."
The regulator said the business appears to be trading using multiple entities. The regulator said these include Unitedmarkets4you and United & Equal, UBS Investment and UBS InvestmentOptions Tech Limited, Cryptex Markets, and Block Chain Exchange Pro.
Those entities were registered at various addresses in London, Manchester and Dominica. The London addresses listed are in the City, in Canary Wharf, or in Regent Street in central London.
The Manchester addresses are in the Piccadilly area, which is a business district of the city.