South Africans have marked Nelson Mandela’s birthday with charitable acts in honour of the former president, whose death in December prompted a global outpouring of tributes.

People picked up litter on Friday, cooked at homes for the elderly and donated food, blankets and other basic necessities to the poor. The United Nations has declared July 18 to be Nelson Mandela International Day.

Organisers had urged people to perform acts of charity for 67 minutes, symbolising the anti-apartheid leader’s 67 years of public service. Graca Machel, Mandela’s widow, joined volunteers who packed food parcels at a convention centre in Johannesburg.

Mandela was jailed for 27 years under white minority rule and led a difficult transition to democracy, becoming president in all-race elections in 1994.

He served one five-year term, evolving into a global statesman and pursuing charitable causes after that.

He died on December 5 aged 95.