By Daniel Wallis

ADDIS ABABA, Feb 1 (Reuters) - Africa's economic growth will slow to 3.5 percent this year and could drop to 2.5 percent in 2010 unless rich nations take action to counter the impact of the global financial crisis, the World Bank said on Sunday.

Experts say initial hopes the world's poorest continent would escape the worst of the turmoil were premature and it will be hit hard by falling demand for commodities, reduced remittances, investment, tourism and domestic tax revenues.

Over the last decade, African economies have grown by an annual average of 5.8 percent, the World Bank says.

"The forecast for this continent before the whole roof came down with the financial crisis ... was actually 6.8 percent," said Obiageli Ezekwesili, its vice president for Africa.

"Now this is being revised: maybe 3.5 percent (in 2009), maybe less than that ... if urgent action is not taken, we could see it lose another percentage point in 2010."

She said it was crucial wealthier states not focus on "insular" domestic responses to the crisis, but heed a call by the World Bank to allocate at least 0.7 percent of any stimulus package to a "vulnerability fund" for African infrastructure.

"They should remember that this crisis was not of Africa's making. Africa is suffering collateral damage," she told reporters on the sidelines of a Feb. 1-3 African Union summit.

"The G8 countries and the rest of the development community must raise their game concerning the resources that Africa needs to sort itself out. The impact of this financial crisis is too devastating on very fragile groups."