The Office of Fair Trading will demand five companies explain claims made in their advertising and on their websites and give details of their business practices to ensure they are complying with consumer protection laws.
The move, yesterday which followed complaints from consumers, came as Which? Money warned that the gold-buying companies offered "shockingly bad value".
Juliet Young, a director in the OFT's consumer market group, said: "Buying gold using the postal service is a relatively new business model, and while innovation often brings benefits for consumers, we want to check that the market and businesses operating in it are developing in a way that treats customers fairly." The OFT is also asking consumers who have used the companies to contact www.oft.gov.uk/goldpost. However, it says it cannot resolve disputes with companies.