Berlin - Nelson Mandela's life has inspired all seeking cooperation and reconciliation in world politics, German President Horst Koehler said Friday on congratulating the South African statesman on his 90th birthday.

"Out of the revolutionary grew a man of reconciliation in South Africa. Nelson Mandela carried hope out into the world," Koehler wrote in an article published on his website and in the daily Frankfurter Rundschau.

Throughout his long career as activist, freedom fighter and politician, Mandela had "always remained faithful to his basic beliefs," he said.

"The driving force behind his action is the struggle against oppression and racism, irrespective of whether it comes from blacks or whites."

Koehler characterized Mandela as a listener and a learner, who respected the views of his opponent.

Noting the challenges that the South African "rainbow nation" faced, Koehler said Mandela's life's work was a compass that showed the way.

The effects extended well beyond the South African freedom struggle to be a "source of inspiration for all who work today for cooperative politics," Koehler said. (dpa)