A tax on financial transactions to fund future bank bailouts should be considered with urgency, British Prime Minister Gordon Brown said on Saturday, a significant departure from London's line to date.

Policymakers are looking at ways to learn from the credit crunch and avoid the need for more massive taxpayer funded bank bailouts in future.

Mindful of the interests of the City of London, Brown has defended the financial sector against more aggressive moves on regulation by other European governments in the past.

"There have been proposals for an insurance fee to reflect systemic risk or a resolution fund or contingent capital arrangements or a global transaction levy," Brown told a meeting of the G20 group of leading countries in Scotland.

He said, though, that all countries would have to act together for Britain to join in.

"I do not in any way underestimate the enormous and difficult practical and technical issues that will need to be overcome that a globally cohesive system requires and raises," Brown said.

"But I do not think these issues should prevent us from considering with urgency the legitimate issues I have discussed."