The Prime Minister has made the issue of tackling shadowy "shell companies" a key priority and it is expected laws establishing a register for firms based in Britain will be included in the Queen's Speech in June.
Anti-poverty campaigners have called for Britain's "tax havens" to set up their own publicly accessible registers, and Mr Cameron said "we should move forward together in raising standards of transparency globally".
He wrote to the leaders of territories and dependencies like the British Virgin Islands, the Cayman Islands and Jersey, urging them to "look closely at what we are doing".
He said public access to a central register was "key to improving the transparency of company ownership and vital to meeting the urgent challenges of illicit finance and tax evasion".
He added: "I am firmly of the view that making company beneficial ownership information open to the public is by far the best approach. It will give businesses and individuals a clearer picture of who ultimately owns and controls the companies they are dealing with."