The UK, France and Germany are understood to be agreed on the argument for a “global responsibility” tax that would cost the likes of Goldman Sachs, Barclays and JPMorgan billions of pounds every year.
Despite the imminent general election, Brown has been pushing the case for the banking levy behind the scenes with French president Nicolas Sarkozy and German chancellor Angela Merkel.
Details of how such a charge would work are still scant. The US has yet to be persuaded to take part, and it is not known whether banks would be taxes based on their assets or their liabilities. But the broad outline is said to be taking shape.
Brown told a newspaper yesterday progress was being made, adding: “The relationship between banks and society has to change.”
The International Monetary Fund is expected to present plans to G20 finance ministers later this month that would see banks make regular contributions towards an emergency bailout fund.