Facebook has banned users from buying advertising space on the social network to promote cryptocurrency and Initial Coin Offerings (ICOs).
The Silicon Valley giant said on Tuesday (30 January) that its new policy "prohibits ads that promote financial products and services that are frequently associated with misleading or deceptive promotional practices" including bitcoin and other virtual currencies.
An ICO is the primary way fintech start-ups raise money and is a similar approach to crowdfunding.
They often promise high returns on investment – but are always high-risk. Many can disappear without a trace taking backers' money with them.
Facebook said in a blog post that such advertising could be "deceptive and misleading".
"We want people to continue to discover and learn about new products and services through Facebook ads without fear of scams or deception," wrote product management director Rob Leathern.
"That said, there are many companies who are advertising binary options, ICOs and cryptocurrencies that are not currently operating in good faith."
The firm said the policy was being kept "intentionally broad" and confirmed that enforcement would also extend to Instagram, its highly popular photo-sharing application.
Users were being encouraged to report any suspicious advertisements that manage to slip through the cracks.
The policy says phrases such as "New ICO! Buy tokens at a 15% discount NOW!" or "Use your retirement funds to buy Bitcoin!" are unacceptable.
The move is the latest attempt to revamp its paid advertising processes. Last year, the social network admitted that its ads had been exploited by Russia's state trolls to spread propaganda.