Maathai on Tuesday said Africans must also fight for good governance, an end to corruption and for education that gives citizens more than just basic schooling.
"We must continue to remove the obstacles and causes of poverty by getting down to the root causes," Maathai said at an African Union summit in Libya.
"There is no reason why we can't raise our moral consciousness to a level where we say it's unacceptable that a dictator in Africa steals money from his people and brings it to a country like Britain where it is protected."
Maathai was awarded the Nobel Peace Prize in 2004 for her devotion to Africa's forests and her desire to end the corruption that has brought their destruction.
She said she hoped audiences at this past weekend's Live 8 rock concerts, aimed at pressing rich nations to drop African debts, realised some banks in wealthy nations, including Britain, were holding money looted by African rulers.
Leaders of the Group of Eight (G8) industrialised nations meet in Scotland starting Wednesday, tasked with tackling African poverty and devising a strategy against global warming.
More than 40% of Africans live on
less than $1 a day
African leaders meeting in Sirte, Libya, urged the G8 to cancel debt owed by their governments, reform international trade and increase aid to fight poverty on the continent.
More than 40% of Africans live on less than $1 a day, while 200 million Africans are threatened by serious food shortages. Aids kills more than 2 million Africans a year.
Anti-poverty campaigners say the G8 leaders have a chance to stop 30,000 children dying every day in extreme poverty by doubling aid to poor countries.
Maathai, who is a veterinary anatomy professor, called on the G8 to cancel all of Africa's debts, saying countries have more than paid back the original loans. Maathai warned that debt relief alone would not solve the continent's problems.
"Cancelling the debt is not the panacea. But there are a lot of people who think it would be, because we keep saying 'debt, debt'," she said.
Removing adverse trade
conditions will help, says Maathai
"Governance is a very important piece of the puzzle and governance has improved in Africa. We're moving in the right direction," said Maathai.
She said removing unfavourable trade conditions was key to helping prop up local economies, particularly agriculture.
"A lot of resources that are extracted out of Africa are not paid for at an adequate price, such as timber from the Congo, to European countries," Maathai said.
Corruption and accountability
But she said foreign help will not end all of Africa's woes.
"I always look to what we Africans can do for ourselves because there's so much we can do which we don't do.
"It's very important that people understand that they must become actively involved in the way they are governed and that they are not just following [leaders]," Maathai added.
"Cancelling the debt is not the panacea. But there are a lot of people who think it would be, because we keep saying 'debt, debt'"
Nobel Peace Prize winner
She said Africans were increasingly demanding an end to corruption and more accountability from their leaders.
Maathai rose to fame for campaigns against government-backed forest clearances in Kenya in the late 1980s and 1990s.
Her Green Belt Movement, made up mostly of women, has gone on to plant about 30 million trees around Africa - 7 million of them in Kenya - in a campaign to slow deforestation and erosion. The movement has spread to about 20 African nations.