The UK'S top taxman is in Switzerland today to broker a historic deal which could see an end to Britain's biggest companies and wealthiest individuals secretly stashing cash in Liechtenstein.

David Hartnett, head of HM Revenue & Customs, flew into Berne last night for top-level negotiations over the future "tax haven" status of Liechtenstein.

Hartnett is proposing a partial amnesty for those tax-dodging Britons who declare the existence of previously undisclosed bank accounts in the tiny alpine state between Switzerland and Austria. As part of the deal HMRC wants Liechtenstein to close all the accounts of Britons who do not voluntarily come forward.

Liechtenstein has come under attack as one of the tax-avoidance capitals of the world amid the fallout of the financial crisis, as the picture of how much money is secretly stashed in bank accounts there has become starker.

As part of plans for a G20 clampdown on tax havens, the likes of Liechtenstein, Switzerland and Monaco face being blacklisted by the international community.