Chancellor Gordon Brown has pledged to waive bills for staging Bob Geldof's Live 8 concert in a move equivalent to writing off £500,000 in VAT.
The gig takes place in London, Paris, Berlin, Rome and Philadelphia on 2 July just before the Gleneagles G8 summit.
Mr Brown hopes he can secure a "big decision" that will transform the "lives of millions" of Africans blighted by poverty and debt.
He has branded his proposals for Africa a "modern Marshall plan".
That is a reference to the US-inspired plan to rebuild Europe in the wake of World War II.
"This is not a time for timidity nor a time to fear reaching too high," said the chancellor as he set out his G8 plans to reporters in Edinburgh.
He also backed a "peaceful" protest in Edinburgh on 6 July.
The G8 talks were "our chance to reverse the fortunes of a continent and our opportunity to transform the lives of millions", he said.
Spice Girls fan?
President George Bush is reported to have said that the US cannot sign up to UK plans to double aid for Africa in the next decade because it does not fit the American "budgetary process".
Mr Brown said he believed his ambition of 100% debt relief was shared by the US.
100% debt relief to pay for education and health
International Finance Facility for immunisation
Doubling of aid from EU nations by 2010
Removal of export subsidies
"What we now have to work out is the mechanics and I believe we will see progress in the next few days on exactly that agenda," said the chancellor.
He said he wanted the British people to play their part in persuading world leaders.
"People have a right to make a peaceful protest and that is something people should be able to do but it must be peaceful, and I think everybody in Edinburgh wants to see that happen," he said.
Mr Brown said he wanted the Spice Girls to reform for Live 8 but added that might be beyond the powers of even Mr Geldof to achieve.
He told GMTV: "I hope Queen will play a part as well and, of course, Paul McCartney.
"Now if all of these came together with the artists in America, then it just shows the power of people to change things and I think young people particularly should know that by coming together you can change the world."
Waiving the bill
This year the UK holds the presidency of both the G8 and the European Union. The government has pledged to make tackling poverty in Africa and climate change its twin priorities.
Conservative international development spokesman Andrew Mitchell endorsed Mr Brown's plans for Africa saying they were "exactly the right thing to do".
"Now is a key moment for our generation in really making a difference to the plight of Africa," he said.
Speaking about Live 8, Mr Brown said: "We are going to waive the bill for the cost of the concert and waive the bill for the cleaning up.
"That is in lieu of any payment of VAT. That is a way of helping this event - probably worth about £500,000."
People wanting to win tickets to Live 8 have been warned not to text earlier than 0800 BST on Monday 6 June.
The text number and a multiple choice question are due to be revealed on BBC television as phone lines open but they will have been published earlier in newspapers.
"We have heard that a lot of people are planning to get the number from the newspapers and text in early," a spokesman said.
"But there is no way to jump the queue. If you text in before 8am, it will cost you £1.50 but your entry won't count."
The line closes at midnight on 12 June and a computer will randomly select the 72,500 entries who will win a pair of tickets each to the Hyde Park gig.