The three main party leaders yesterday committed themselves to tackling the plight of the world's poorest countries in speeches to mark World Poverty Day.

In an emotional 25-minute unscripted speech, Mr Blair told a rally at the Old Vic Theatre in London: "We have to make 2005 the year of the new beginning for Africa."

It was time, he said, with the help of other leading wealthy nations, to end the "scandal" of death from Aids, malaria and other preventable diseases. In a live satellite link from New York, President Bill Clinton offered support for Mr Blair's initiative.

"It's not only achievable, it is morally right," Mr Clinton said. "We can do this, but it requires leadership, and Tony Blair, Gordon Brown and New Labour are providing that leadership."

Mr Blair said Britain would use its presidency of the G8 leading industrialised nations to make assistance for Africa a key priority and end the "scandal" of thousands dying needlessly every day.

He said that while under the Conservatives, the proportion of national wealth devoted to international aid had halved, under Labour it had risen every year since they came to power in 1997. "If we are given the chance and are re-elected, I can make you this commitment. We will work night and day to end the scandal of poverty in Africa."

In the live satellite linkup, Mr Clinton said that, for a modest amount of money, the world's richest nations could improve health, education and the economy of the poorest. Also speaking at the rally, Chancellor Gordon Brown said that 2005 should be the "year of deliverance from debt" for the poorest nations.

Tory leader Michael Howard sought to play down political differences on the issue, saying that all three main parties shared the goal of achieving the UN target for aid by 2013 while working to cancel debt.

"I'm particularly pleased that the cause of making poverty history is something that has united the parties in this country," he said on a visit to Tabernacle Christian Centre in west London.

However, Liberal Democrat leader Charles Kennedy insisted that his party would move faster than the others, reaching the UN aid target by 2011 at the latest. He called for 100 per cent debt relief for the poorest countries as well as action to tackle the spread of Aids and HIV.