IMF studies range of possible levies on banks

But Olivier Blanchard stressed that the IMF, which has been asked by the Group of Twenty leading nations to explore the issue, aimed to ensure any levy did not stymie a recovery in lending by financial institutions.

Some possible levies could recoup part of the billions of dollars of taxpayers' money ploughed into banks to prevent them from failing during the global financial crisis, Blanchard said in an interview.

"At this stage we are working on many options and these include a Tobin-like tax on transactions and taxes looking at the past to see if there is any way of getting the money back: taxes on past profits or taxes on assets," he said.

Blanchard's ultimate boss, IMF managing director Dominique Strauss-Kahn, told Reuters on Sunday that the fund was not working on a so-called "Tobin tax" on financial transactions, because such a tax would risk being unworkable.

However, Blanchard said a Tobin tax was still being studied on a purely technical basis, despite opposition to the tax from some nations, notably the United States.

"We all understand that a Tobin tax is going to introduce some distortions...Will people find a way of avoiding it altogether though?" he said.

"It may make sense to have some kind of tax, but we have to be careful when we do this that we don't squeeze the capitalisation of banks, and so delay lending by another six months," he said. "We can't just take the money and run."

The IMF is also looking at the possibility of levying insurance fees on banks; the fees could be used to build up funds that would conduct future bank rescues, relieving taxpayers of the burden.

"Then there is the much more important question of how do we do it in the future? Basically, taxing firms for the risk they impose: some form of 'insurance premia'," Blanchard said. "Whether we call these insurance premia or taxes is only a matter of semantics."