A British-led bid to crack down on offshore tax evasion has been backed by 20 countries and territories, Chancellor George Osborne has said.
The initiative to automatically share information on the real owners of companies set up with Germany, France, Spain and Italy, has been joined by Sweden, Gibraltar, Isle of Man, and Montserrat, as well as other countries.
Participating countries and territories exchange data between tax and law enforcement agencies on company beneficial ownership registers and new registers of trusts to try to ensure more effective investigation of financial wrongdoing and tax-dodging.
Mr Osborne said the growing international group would deal a blow to tax evaders.
"Only a week after Britain launched this initiative with some of our closest European partners, it's gaining the international support that will be vital to make it truly effective.
"I welcome the early commitment made by Gibraltar, Isle of Man and Montserrat to participate and call on all of the remaining Overseas Territories and Crown Dependencies to do likewise," he said.
"It should be clear to all countries and tax jurisdictions that the world is moving firmly in the direction of greater tax transparency and the UK will continue to push for an internationally-agreed blacklist for those that refuse to do the right thing."
Prime Minister David Cameron emphasised the need for international co-operation on dealing with off-shore tax evasion during a joint press conference with US president Barack Obama.
Mr Cameron said he expected progress on this issue at a major anti-corruption conference set to be held in London.
Countries joining the initiative include The Netherlands, Romania, Finland, Slovakia, Latvia, Croatia, Belgium, Ireland, Slovenia , Denmark, Malta, Lithuania, Cyprus, Bulgaria, Portugal, Estonia, Greece and Czech Republic.