REUTERS - Mar 27 - Twitter is banning cryptocurrency ads, joining Facebook and Google in a clampdown that seeks to avoid giving publicity to potential fraud or large investor losses. The prohibition will cover advertising of ICOs - crowdfunding used to raise cash by creating new coins - as well as token sales. The new policy will also ban ads by cryptocurrency exchanges and cryptocurrency wallet services, unless they are public companies listed on certain major stock markets. Facebook has restricted crypto-related adverts, while Google announced a ban that comes into force in June. The price of bitcoin, already 4% in the red on Monday, fell further after the Twitter announcement.