Maathai, 64, is the first African woman and environmentalist to receive the prestigious award.

She was honoured for her campaign to save Africa's forests and for standing at the "front of the fight to promote ecologically viable social, economic and cultural development in Kenya and in Africa".

Maathai, who won the prize on 8 October, received the award plus $1.4 million at a formal ceremony at Oslo's city hall on Friday - the anniversary of the death of prize founder Alfred Nobel.

Committee president Ole Mjoes presented her with the Nobel diploma and gold medal in the presence of Norway's King Harald.

Speaking on Thursday, Maathai said more women need to do jobs where they make decisions if they are to play a role in peacemaking.

Empowering women

"One reason why women are not as active in peacemaking as they should be is because they are not in the decision-making," Maathai said.

Some previous winners

1994: Yasir Arafat, Yitzak Rabin, Shimon Peres

1993: Nelson Mandela

1989: Dalai Lama

1979: Mother Teresa

1978: Anwar Sadat and Menachem Begin

1973: Henry Kissinger

1964: Martin Luther King

"It is very difficult if you are on the outside shouting to people who are inside the house... We must put ourselves in the position where our voices can be heard inside the house."

Maathai said she hoped the prize would help empower women around the world and especially in Africa.

"I believe that a great honour such as this bestowed on an African woman can only encourage and empower women, especially the African women. And it can only make men stand up and wonder what has hit them," she said with a broad grin.

At a separate ceremony in Stockholm on Friday, the winners of the Literature, Medicine, Physics, Chemistry and Economics prizes received their awards from King Carl XVI Gustaf in Stockholm's Concert Hall.