WASHINGTON, Aug 1 (Reuters) - The United States on Wednesday took steps to freeze the U.S. assets of five key members of the Italian-based Camorra, also known as the Naples Mafia, and one of Europe's largest criminal groups involved in kidnapping, money laundering and extortion.

Americans and U.S. businesses are prohibited from doing business with the five blacklisted Camorra members, three of whom are serving life sentences for murder and conspiracy, the U.S. Treasury said in a statement on its website.

Treasury said the Camorra members on the blacklist included Mario Caterino, Giuseppe Dell'Aquila, Paolo di Mauro, Antonio Iovine and Michele Zagaria.

The Treasury would not comment on the amount of assets the group's members have under U.S. jurisdiction, but it said in the statement that today's action would help "cast an even larger net to expose their financial facilitators and associates, wherever they may operate." (Reporting By Rachelle Younglai; Editing by Stacey Joyce)