Britain is entering into talks with three tax havens which could help raise £10 billion for the Treasury by 2015, it was revealed today.
Chancellor George Osborne confirmed that the UK was also in discussions with Switzerland which could see the Alpine state help to tax British citizens' assets in secret accounts.
Switzerland is also expected to introduce a withholding tax on new deposits while preserving its banking secrecy laws.
A banking transparency arrangement struck recently with Liechtenstein appears to be delivering more than the £1 billion predicted in the Budget, officials indicated.
Now three further tax havens, which have not been identified, have agreed to go into talks with Britain next week over similar arrangements.
If all of the deals are successfully concluded, the three unnamed tax havens, Liechtenstein and Switzerland could between them help Britain raise an estimated £10 billion over the coming years.
Mr Osborne said: "We are all in this together, and that includes those who try and evade tax.
"We are in the process of striking a deal with Switzerland and more deals will follow.
"In total, this will raise many billions of pounds which the previous government failed to do. This is tough but fair."