Nairobi: Kenyan environmental activist Wangari Maathai, the first African woman to be awarded the Nobel Peace Prize, has died of cancer at the age of 71, her family said on Monday.

"It is with great sadness that the family of professor Wangari Maathai announces her passing away on September 25, 2011 at the Nairobi hospital after a prolonged and bravely borne struggle with cancer," said a statement issued via the Green Belt Movement she founded.

Maathai became a key figure in Kenya since founding the movement in 1977, staunchly campaigning for environmental conservation and good governance.

She won the 2004 Nobel Peace Prize for her reforestation work in her native Kenya, the first African woman, the first Kenyan and the first environmentalist to receive this honour.

Her organisation has planted some 40 million trees across Africa.

The first woman in east and central Africa to earn a doctorate, Maathai also headed the Kenya Red Cross in the1970s.

Aside from her conservation work, Maathai was elected an MP in 2002 and then named the Environment Assistant Minister, a position she held between 2003 and 2005.

For more than a decade from the 1980s, her movement also joined the struggle against the dictatorial regime of Kenya's former president Daniel Arap Moi, with Maathai repeatedly teargassed and beaten by police.

During the time, she famously campaigned against the construction of a high-rise building at a park in central Nairobi, stopped the grabbing of a forest outside the city and successfully pressed for the release of 51 political prisoners.

The award-winning Maathai in recent years founded green groups and launched several campaigns against climate change and environmental protection.

Outside Kenya, Maathai was involved in efforts to save central Africa's Congo basin forest, the world's second largest tropical forest.

Maathai, who was divorced, leaves behind three children and a granddaughter.

"Professor Maathai's departure is untimely and a very great loss to all who knew her as a mother, relative, co-worker, colleague, role model, and heroine or who admired her determination to make the world a more peaceful, healthier, and better place," said the statement.

(Agencies)