Brown in 100% debt relief pledge
Speaking at the World Economic Forum in Davos, Mr Brown said he hoped to persuade his colleagues to commit to the goal by the end of the year.
His pledge has already won support from France's new Finance Minister, Herve Gaymard.
Both politicians promised to engage with Global Call to Action Against Poverty, a pressure group formed on Thursday at the World Social Forum in Brazil.
Held to account
Mr Brown also promised that the current round of trade talks would be the "first that is in the interest of developing countries".
Next Friday's meeting of the G7 finance minister would put debt relief and development issues at the top of its agenda, Mr Brown said, adding that this had been agreed with all the ministers from the world's richest countries.
The meeting will also be addressed by former South African President Nelson Mandela, who will argue the case for comprehensive debt relief.
Anti-poverty campaigners like rock star Bono and former president of Ireland Mary Robinson, now president of Oxfam International, praised the UK and French finance ministers, but warned that they would hold them to account at the end of the year.
Change of game
Global Call to Action Against Poverty is supported by a wide range of organisations, from Action Aid and the All Africa Council of Churches to global trade unions and World Vision International.
The organisation plans three action days this year to lobby G7 governments with peaceful demonstrations.
This is supposed to be a talking shop but instead something very real has come out of it
U2 singer Bono Mrs Robinson said there was still a lack of political will to tackle poverty, despite the support from the UK and France, and the promise by German Chancellor Gerhard Schroeder to support a major British debt relief initiative.
Mr Schroeder had told delegates at the World Economic Forum that he would back a UK proposal to increase funding for the United Nation's Millennium Development Goals by refinancing the so-called International Finance Facility.
He also backed a proposal made by French President Jacques Chirac on Wednesday to tax speculative cross-border financial transactions, a suggestion that has been greeted with scepticism in Britain and the United States.
Bono, speaking at Davos, described Mr Brown's plan as a turning point in the campaign to tackle world poverty.
"There are moments in these campaigns when you feel the game change. Today I knew the game had changed.
"This is supposed to be a talking shop but instead something very real has come out of it."