The agreement thrashed out by Gordon Brown, the Chancellor, is estimated to provide up to pound;1bn in new money for Africa through debt relief. But it is a "very small amount," said Anne Jellema, of the Global Campaign for Education, when compared to the pound;3bn Unicef, the United Nation's children's fund, estimates is needed annually just to provide education for all primary children by 2015.
The debt write-off covers 18 countries, 14 of them in Africa, including Ghana, Ethiopia, Uganda and Zambia. Nine others are expected to qualify within 18 months.
"This is a small number of countries and not enough to make a substantial advance in providing education for all," Ms Jellema said. The initiative is seen as "an accounting exercise to write off debt that is not being paid, so it will not always mean more money," she said.
However, Romilly Greenhill, of ActionAid, said up to pound;1bn would be money that would otherwise go towards paying long-standing debts to Western banks and institutions.
ActionAid welcomed the debt-relief announcement as a "good first step". Ms Greenhill said "debt relief is a long-term predictable source of money and good for ongoing education expenditure such as teachers' salaries".
However, she said at least 40 other countries also need 100 per cent debt relief.
Countries who will benefit must show that they will use the extra money to ease poverty, including spending on health, education and development.
Campaign groups are calling for up to pound;22bn in aid on top of debt reduction to pull Africa out of poverty. "That aid should include pound;3bn needed for education," Oxfam's Max Lawson said.
Pressure on the G8 leaders continued this week as prominent women, including writers Germaine Greer and Helen Fielding, called on them to help get more girls into school.
In a letter to finance ministers they urged the G8 to "open the purse strings" to ensure all children can go to school, particularly girls. Some 60 million girls are not educated, the equivalent of the population of Britain, according to Save the Children.
Children from more than 100 countries and 6,000 schools in the UK have made up to a million cut-out figures to represent their peers who are out of school.
The child-shaped messages, dubbed "buddies" or "friends", represent the 100m children worldwide who receive no formal education. Each buddy represents a direct plea from a child to G8 leaders to honour their promise to ensure every child receives an education by 2015.
Opinion 23 www.sendmyfriend.org