David Cameron must "stop pussyfooting around" and take tough action on tax havens and those avoiding tax, Labour's Jeremy Corbyn is set to demand in response to the Panama Papers leaks.
The Labour leader will use the launch of his party's local government campaign in Harlow later today to pressure Mr Cameron over the leaks, which have exposed schemes by wealthy individuals to cut their tax bills.
Mr Corbyn will argue the avoidance of tax by corporations and wealthy individuals is starving public services of funding and say that there cannot be "one set of rules for the wealthy elite and another for the rest of us".
Mr Cameron has found himself embarrassingly dragged into the scandal after it was reported that his father Ian ran a network of offshore investment funds that built the family fortune, but avoided having to pay tax in the UK.
Downing Street insisted it was a "private matter" whether the Cameron family still had funds in offshore investments.
There is no suggestion that the arrangement - or others exposed by the leak of 11 million confidential files from the Panama-based law firm Mossack Fonseca - were anything other than entirely legal, or that Mr Cameron's family did not pay the UK tax due on any repatriated assets.
Speaking in Harlow, Mr Corbyn is due to say:
HMRC insists that all of the Crown Dependencies and Overseas Territories have made "significant progress" on tax transparency.
Mr Cameron has championed transparency at a series of international summits and legislation forcing British companies to disclose who owns and benefits from their activities comes into force in June.
But despite several years of pressure, few UK Crown Dependencies and Overseas Territories - said to make up a large part of the tax havens referred to in the papers - have taken concrete action to open up their books.