Mrs Maathai, whose Green Belt Movement planted an estimated 45 million trees in Kenya, died last month of cancer.

Thousands of mourners lined the route of the procession to the funeral in Uhuru National Park in Nairobi.

President Mwai Kibaki praised her courage, tenacity and "selfless service to the nation".

Mrs Maathai, who died on 25 September, was the first African woman to win the Nobel Peace Prize, in 2004. She won the award for her campaigns to promote conservation, women's rights and transparent government.

Because she opposed cutting down trees, her remains were placed in a bamboo-frame coffin, made of water hyacinth and papyrus reeds and draped with a Kenyan flag. After the funeral, she was cremated at a private ceremony.

In 2008, Mrs Maathai was tear-gassed at a protest against President Kibaki's plan to increase the number of ministers in his cabinet.

"Wangari's legacy goes beyond Kenya - all over the world," said Prime Minister Raila Odinga. "We have lost a dedicated selfless Kenyan patriot."