British Prime Minister Gordon Brown says some of the world's largest economies have agreed to a global tax on banks.
Brown told The Financial Times that Britain, France and Germany support the idea and that he hopes the U.S. will join them.
"The relationship between banks and society has to change," he said.
The levy would cost American banks an estimated $10 billion.
Brown says he hopes the G20 summit of leading economic powers will agree to the plan in Seoul, South Korea in November along with other regulations for the banking system.
In January, President Obama unveiled a plan to tax risky assets of large U.S. financial institutions. The plan was intended to recover the huge cost of the recent bailout of the sector.