Nelson Mandela, left, waves from the stage as U.S. actor Will Smith smiles from behind at the 46664 charity concert in honour of Mandela's 90th birthday in London on June 27. (Lefteris Pitarakis/Associated Press)

Former South African president Nelson Mandela is taking legal action against an art gallery in London to prevent the sale of sketches that are attributed to him.

The anti-apartheid icon, who recently celebrated his 90th birthday with a massive concert in London, has disassociated himself from an exhibition being held at the Belgravia Gallery.

"Mr. Mandela has given us instruction to take urgent, appropriate steps against Belgravia Gallery to stop any marketing, distribution and selling of artwork associated with his name," said a statement released Friday by the Johannesburg law firm Chuene Incorporated.

The sketches are scenes from Robben Island prison, where Mandela was incarcerated for 27 years. He served as South Africa's president from 1994 to 1999.

Anna Hunter, managing director of Belgravia Gallery, said they had heard nothing formally.

She said she witnessed Mandela signing the works in 2002, and gave a speech alongside him when he launched them in South Africa.

"I am surprised, because they are wonderful and historically interesting pieces of art. He has done very colourful images of a place that was so dark and grey," Hunter told The Guardian newspaper.

Views of cell, lighthouse, church

The lithographs, created by Mandela in 2001 and 2002 when he returned to his former jail, include views of his cell, the lighthouse, the church and harbour.

They were put up for sale three years ago by the same gallery, but withdrawn when Mandela began legal proceedings.

At the time, Mandela alleged the prints were being marketed with false signatures, and that proceeds were not reaching their destination — charities for the homeless and for AIDS.

Lawyer Bally Chuene said a South African court granted a court order in 2005 to prevent the gallery from marketing, selling or distributing any artwork under Mandela's name.

He said the action was taken, once again, because there are concerns that the proceeds of sales of artwork would not be given to charities and that Mandela's signature may have been forged.

Prices for the lithographs at the Belgravia gallery range from £6,000 to £15,000 ($12,100 to $30,340 Cdn).