Aid to Africa needs to increase by at least 60% if poverty is to be cut, the World Bank said.
More than 315 million Africans live on less than a dollar a day
World Bank regional vice president Gobin Nankani said that financial help to Africa has remained flat, despite pledges by donors to increase it.
Aid flow to Africa reached 16bn euros ($20.7bn; £11.1bn) in 2002, but dropped to 15bn euros in 2003.
Mr Nankani said that 2005 is an opportunity to reverse this trend in international aid.
He added that financial assistance should match the progress African countries had made in recent years in terms of governance.
"We have done an analysis in the World Bank which suggests that an immediate increase of 60% on current levels will be easily absorbed and productively used by the better-performing countries of Africa."
Mr Nankani spoke at the end of a two-day African partnership meeting in Johannesburg, South Africa, attended by African government officials and the international donor community.
He added that the World Bank welcomed the UK initiative to increase debt relief and give more aid to African countries.
Getting rid of agricultural subsidies is key
New trade deal
Mr Nankani also called for a new global trade agreement to enable Africa to benefit from trade.
He pointed out that rich nations spend $1bn a day in agricultural subsidies.
Tariffs on Africa's processed exports need to fall, he said.
"For example, the tariff on roasted coffee is nine times the tariff on raw coffee beans. With that kind of bias, it is very difficult to help African trade," added Mr Nankani.
More than 315 million Africans live on less than $1 a day.