Maathai, a Christian who has led plantings of 30 million trees across Africa to combat deforestation, said an annual tree-planting drive could symbolize revival for all peoples.

She suggested plantings at Easter, when Christians believe that Christ was crucified on a wooden cross. A tree must have been felled to make the cross, she said.

"We could make it a day to say thank you for those of us who believe in the Bible, those of us who believe in the Koran," she said shortly before the prize ceremony in Oslo City Hall.

"Even in the eastern religions they are very respectful to the other species and so it could be something to unite all of us," she added.

She suggested that the tree-planting day be set for Easter Monday, a day after Christians believe Christ rose from the dead, and said the day could be shared worldwide by other religious groups and non-believers.

"Most of Africa is Christian, certainly south of the Sahara, that is where much of the desertification is taking place," Maathai said.

Maathai, 64, is the first African woman to win the Nobel Peace Prize, which comprises a check for 10 million Swedish crowns ($1.48 million), a gold medal and a diploma.

She is being honored for work to protect the environment and to promote peace, democracy and women's rights.

She said Easter Monday could also be a day for wider work to protect the environment, ranging from cleaning beaches to slowing silting of rivers.