Prime Minister Gordon Brown said the introduction of a global tax to reduce risky behaviour by banks was "worth looking at", as he prepares for a G20 summit next weekend.
But Brown said greater cooperation between countries to stop excessive risk taking was required before such a tax could be considered.
France has proposed introducing a tax to be levied on every financial transaction, known as a Tobin Tax, with the billions of euros raised to be used to support economic development.
Brown said such an idea was worth consideration, but global cooperation that is "cemented" and "action that is successful against tax havens" were required before taking any steps towards the measure.
