The four-hour memorial service for Nelson Mandela is underway in the South African city of Johannesburg.

The rain is pouring down but it has not dampened the spirits of tens of thousands of people who have filled the FNB stadium - the place where Mandela made his last public appearance at the World Cup in 2010.

More than a hundred countries are represented among the special guests at the memorial service, who include US President Barack Obama and David Cameron.

Obama will be giving a speech during the service.  Representatives of different faiths have also been in attendance.  They have offered prayers for the future of South Africa and the world, and given readings.

Mandela, anti-apartheid hero and South Africa's first black president, died last Thursday at the age of 95.

The South African government has assured that it has put in place its tightest security plan ever, both at the 95,000 capacity FNB stadium where the event is being held – at which Mandela gave his last public appearance in 2010 - and at three overflow stadiums across the city, which give a further capacity of 125,000 on a first come first served basis.

A state funeral will take place on Sunday, and Mandela's body will be buried in his home village of Qunu in Eastern Cape Province.

Prince Charles will attend the state funeral of Mandela on Sunday, while David Cameron is representing Britain at the public memorial today.

The BBC's live stream is available to watch here
ABC News is running a live stream of today's memorial service with commentary here
ITV also has a live stream here