A lawyer for Nelson Mandela, who served as South Africa's president from 1994 to 1999, says the elder statesman has yet again demanded an end to a London exhibition of lithographs that reportedly bear his signature.

Balley Chuene said Friday that Mandela, who turns 91 next Saturday, has officially distanced himself from the Belgravia Gallery's exhibit of works purportedly drawn by him.A lawyer for former South African leader Nelson Mandela says some illustrations to be exhibited at a London gallery, purported to be by the anti-apartheid hero, are unauthorized reproductions.A lawyer for former South African leader Nelson Mandela says some illustrations to be exhibited at a London gallery, purported to be by the anti-apartheid hero, are unauthorized reproductions. (Associated Press/File)

The gallery is launching the show on Monday and its managers have not commented on Chuene's declaration.

Chuene said he wrote to the gallery last week asking it to "desist immediately" in its exhibit but he did not receive any reply.

"[Nelson Mandela] did not sign those artworks," he said.

The lithographs — which include sketches of Robben Island and Mandela's cell where he was incarcerated for 27 years — have been at the centre of a disagreement between Mandela and the gallery for several years

A South African court granted an order in 2005 to prevent the gallery from marketing, selling or distributing any artwork under Mandela's name.

Last year, a similar exhibition by Belgravia was shut down after Chuene wrote to the gallery warning against it.

Mandela's lawyers contend that unauthorized reproductions had been made and were being sold under the guise of benefiting Mandela's charities for homeless children and AIDS victims.

Chuene said these unauthorized reproductions are part of the current exhibit, which is slated to run until July 31.

"They are being very opportunistic," he said. "The purported artwork does not have Mandela's blessing."

Belgravia gallery executive Anna Hunter has previously said she had commissioned South African handwriting specialist Cecil Greenfield to examine her stock of 100 prints. Greenfield verified that they all have a genuine signature.

Hunter said she also personally watched Mandela sign the lithographs back in 2002.

With files from The Associated Press