Archbishop Desmond Tutu on Friday praised the "wonderful" decision to award US President Barack Obama the Nobel Peace Prize.

"It is a very imaginative and somewhat surprising choice. It is wonderful," Tutu told reporters.

"He has had a very significant impact. It (his presidency) has changed the temperature and almost everybody feels a little more hopeful about the world," he said.

Tutu won the Nobel prize in 1984 for his long battle for a non-violent end to South Africa's apartheid system of racial segregation.

He is still considered as the voice of the nation's conscience and is active in promoting peace around the world.