Gordon Brown: "A very big breakthrough indeed"

Mr Brown is due to lead efforts to have the plans approved at the Cologne summit of the G8 group of the world's richest industrial nations and Russia, which begins on Friday.

Speaking before flying from London, Mr Brown paid tribute to the late Cardinal Basil Hume, who died on Thursday, for his work with church groups and other campaigners to pressurise wealthy governments to agree to debt relief.

Cardinal Hume, he said, had been "a good man and a great man and who was one of the crusaders for justice for the world's poor."

Mr Brown, who has long advocated debt relief, said the deal on the table at the G8 summit was "not the summit of our ambitions, but a very big breakthrough indeed."

Under the proposals, $100bn of debt payments and loans would be cancelled.

'Helping the world's poor'

"So two thirds of the official debt of the poorest countries will, if we reach this agreement, today, be written off," Mr Brown said.

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"More than that money will go from savings on interest payments to poverty relief, health and education.

"And we will, for the first time, decide to sell IMF gold to make it possible and set up a millennium trust fund to which governments, and perhaps even companies, will contribute, that will help pay for that debt relief," he said.

Gordon Brown says he will ensure the money freed up by debt relief will not be squandered

Mr Brown also insisted that as part of the deal measures would be put in place to explicitly link debt relief to poverty relief.

"It is a condition of what we are doing that the money saved form interest payments should not go to military expenditure or to bureaucratic excesses or corrupt practices or anything like that, that it must go to helping the world's poor," he said.

The agreement is expected to be ratified on Saturday and then goes to the autumn annual meetings of the World Bank and the International Monetary Fund.