The owner of a billboard dedicated to Nelson Mandela in southern India has been left red-faced after a photo of actor Morgan Freeman had been used instead of the iconic South African freedom fighter.

The sign had been erected on a roadside in the southern city of Coimbatore as part of memorials across India and the world to Mandela, who died on December 5.

But Freeman's face loomed large above over smaller images of Martin Luther King, Mother Teresa and Mahatma Gandhi.

Morgan Freeman played Mandela in the 2009 film Invictus.

"We should be proud that we were part of an era when they lived," the Tamil-language condolence message read.

Cloth merchant Chandrashekhar, who paid for the board in a private capacity as a mark of respect to the former South African leader, said it was a mistake by the designer.

"We will replace it with the correct picture of Mandela," he said, adding he did not know how the gaffe happened.

A photo of the billboard has been widely circulated on Twitter.

India declared five days of national mourning for Mandela, who was hailed as a "true Gandhian" and a "great friend" by the country's leaders.

AFP