The whole world has been invited to leave Nelson Mandela a birthday message on what will be the biggest virtual birthday card in history. 

Launched globally on June 16 by Mandela’s Aids awareness organisation, 46664, the campaign allows all those with access to a mobile phone or the internet to send a 90th birthday message to the world’s most popular 90 year-old.

All messages will be published on the www.happybirthdaymandela.com website.

SMSs cost R20, and profits from the messages will go towards all of Madiba’s charitable organisations: the Nelson Mandela Foundation, the Nelson Mandela Institute for Education and Rural Development, the Nelson Mandela Children’s Fund, the Mandela Rhodes Foundation and 46664.

The campaign is supported by Vodacom and will run up to and including the day of Mandela’s birthday on the 18 July.

Among the high profile figures who have already sent messages are Bill and Hillary Clinton, UK Prime Minister Gordon Brown, entrepreneur Richard Branson and musicians Sheryl Crow and Josh Groban.

Speaking at the launch of the South African leg of the campaign, CEO of the Nelson Mandela Foundation Achmat Dangor said the primary purpose of the campaign was to allow as many people as possible to wish Madiba a happy birthday.

Asked how Mandela might feel about this outpouring of love, Dangor said: "Knowing the modest man that he is, he would be pleased, but also a little embarrassed. Embarrassed in a good way! He always feels that he as an individual should not be celebrated. He's always said ... that his values should be celebrated."

The launch was attended by South African singer and 46664 Ambassador Yvonne Chaka Chaka. Her message read: "Madiba, no words can describe how the whole world respects and loves you for all that you have done. Now, on your 90th birthday, all I want to say is that you are the Man of the World, Warrior of our Salvation. As people you have given us back our dignity."

Chaka Chaka said she hoped that billions of people across the world would send in their birthday wishes. "There are 6.6 billion people in the world; I would like to see the SMS campaign receive at least 4 billion messages!"

Since the global launch, over 40 000 messages have been sent to Mandela from 120 different countries across the world. Tanzania has sent the most messages with just under 30 000 messages coming from East African country while South Africans have only sent 460 birthday wishes.

So come on South Africans! Visit www.happybirthdaymandela.com to write your message for Madiba or send an SMS to 46664. For those residing outside of South Africa, click here for your country code.