Determined to keep the pressure up on so-called tax havens, senior US Democrat Senator Carl Levin wants the US government to put forward tough sanctions at this month’s Group of 20 summit against banks and nations which are sheltering tax dodgers, according to Dow Jones.

Mr Levin, a senator for Michigan, said in a letter to President Barack Obama that the US should seek G20 approval of sanctions for tax havens, including prohibiting G20 banks from doing business with financial institutions that are found to be impeding tax enforcement.

The approach is similar to an anti-money-laundering sanction already in place in the US.

Politicians such as Mr Levin have sought to put the fight against international offshore centres high up the policy agenda since the eruption of the credit crisis about two years ago. However, in their defence, centres such as Switzerland, The Cayman Islands and elsewhere have argued they are being unfairly blamed for financial problems in large nations.

In Mr Levin’s letter, he is reported to have written: "If ... a tax haven bank refused, for example, to cooperate with requests about U.S. clients using the bank to hide assets and evade tax obligations, the United States could prohibit U.S. financial institutions from doing business with that bank, until it provided the requested information.”

The G20 summit will be held on 24 – 25 September in Pittsburgh.