A set of 20 lithographs will go on sale today. Costing between $2 600 to $3 000 (R36 000 - R42 000) per copy, they may seem a little expensive for simple line drawings shaded with blocks of colour. But their subject is the notorious former apartheid prison Robben Island, and the artist is Nelson Mandela.

An exhibition of Mandela's new artwork opens at the island today; it is the second series of charcoal and pastel drawings of his prison home of 18 years. The first appeared at London's Belgravia Gallery last year.

The former South African president, who shared the 1993 Nobel Peace Prize for his campaign to end whites-only rule, was tutored by the 26-year-old Cape Town artist Varenke Paschke in the run-up to the exhibition.

Paschke said her celebrity student was "very keen". "His work is straight down the line, no frills," she said.

She described Mandela's home as relaxed, with friends such as his fellow former inmate Tokyo Sexwale and U2's singer Bono dropping in during lessons. The new series cements Mandela's status as a blossoming artist, despite being in his 85th year, as well as a best-selling author, internationally respected statesman and anti-war campaigner. Last week he lambasted the British prime minister, Tony Blair, for being "foreign minister of the United States".

He is expected to sign as many as 250 prints per hour, which will go on sale in order to raise money for his children's foundation.

Oprah Winfrey is one of the collectors of his work.

Mandela has said of his artwork: "I have attempted to colour the island sketches in ways that reflect the positive light in which I view it ... to project the idea that even the most fantastic of dreams can be achieved if we are prepared to endure life's challenges." - Guardian Unlimited Â