HSBC’s Swiss banking arm helped wealthy customers dodge taxes and conceal millions of dollars of assets, doling out bundles of untraceable cash and advising clients on how to circumvent domestic tax authorities, according to a huge cache of leaked secret bank account files...[T]he...files, which cover the period 2005-2007, amount to the biggest banking leak in history, shedding light on some 30,000 accounts holding almost $120bn (£78bn) of assets.The revelations will amplify calls for crackdowns on offshore tax havens and stoke political arguments in the US, Britain and elsewhere in Europe...HSBC...has now admitted wrongdoing by its Swiss subsidiary. “We acknowledge and are accountable for past compliance and control failures,” the bank said in a statement. The Swiss arm, the statement said, had not been fully integrated into HSBC after its purchase in 1999, allowing “significantly lower” standards of compliance and due diligence to persist...The Labour party said: "Tax avoidance and evasion harms every taxpayer in Britain, and undermines public services like the NHS..."