The body, headed by Mark Everson, is planning to stop US financial institutions from setting up structures outside the country that avoid tax through a partnership with a foreign bank. The set-ups see the institution and its foreign partner pool assets and pay tax on the assets in the country where they are held.

The US company then claims a tax credit on the foreign tax paid to avoid double taxation, while the foreign partner also claims a tax credit. This structure allows the foreign partner to lend cash to the special purpose vehicle at lower interest rates.

The IRS has put forward proposals to block the use of special purpose vehicles which will be debated at a public hearing in Washington at the end of July.

The move comes as US politicians launch a new wave of attacks on the tax avoidance industry both at home and worldwide.

Presidential candidate Barack Obama has backed a bill to crack down on tax havens in particular.