JOHANNESBURG - Nelson Mandela's foundation has denied reports of his death after the iconic former South African leader fell victim to a hoax on Internet micro-blogging site Twitter over the weekend.

"Nelson Mandela is well and on holiday," a spokesman for the Nelson Mandela Foundation, Sello Hatang, said in a statement late Saturday, denying "unsubstantiated reports about Nelson Mandela's health."

Reports that the 92-year-old anti-apartheid crusader and Nobel Peace Prize winner had died spread on Twitter on Saturday.

On Sunday, Twitter users reacted with indignation to the hoax.

"Nelson Mandela didn't die!! Who would make such a terrible lie," one user wrote. "Twitter has been the place for too many death jokes," another added.

Similar hoaxes on Twitter have targetted singer Aretha Franklin and actors Charlie Sheen, Johnny Depp and Morgan Freeman.

After his withdrawal from public life in 2004, Mandela created the Nelson Mandela Foundation, the Nelson Mandela Children?s Fund and the Mandela Rhodes Foundation to continue humanitarian work on his behalf.

Mandela, South Africa's first black president, is increasingly frail and has not appeared publicly since the closing ceremony of the 2010 FIFA World Cup in Johannesburg.