A fresh onslaught on offshore tax evasion is to be mounted by UK Revenue & Customs early next year when it targets customers of 25 building societies and foreign banks with British operations.

The move follows the Revenue’s success last year in forcing five British high street banks to disclose details of secret offshore accounts. That assault, accompanied by the offer of an amnesty, recovered around £400m in unpaid taxes at a cost to the Exchequer of just £6.5m.