* Desmond Tutu's blessing concludes the service, amid cries of "long live Nelson Mandela".
Mandela's body will be kept in Pretoria for three days and his state funeral will be held in Qunu on Sunday.
* The memorial service is now drawing to a close.
Organiser Cyril Ramaphosa thanks those made the effort to come to the service.
* The final of the five world leaders to speak on Tuesday is President Raúl Castro Ruz from Cuba.
He says Mandela was the "ultimate symbol of dignity... a prophet of unity, of peace and reconciliation."
"Mandela has led his people in the battle to open the way to a new South Africa - a nation bent on overcoming the consequences of colonialism, slavery, and racial segregation," he said.
* As Indian President Pranab Mukherjee took to the stage, he was briefly interrupted by organisers as they tried to silence "enthusiastic" bands in the upper stands of the stadium.
India declared five days of mourning following the death of Mandela, and Mukherjee says he was one of most influential personalities of the last century.
Mukherjee says Madiba built a "truly rainbow nation", and that India stood with South Africa in its hour of mourning.
* Service organiser Cyril Ramaphosa says they won't keep the crowds there for much longer because of the rain. He says there are three more speakers, and president Jacob Zuma will keep things "brief".
* Next to speak is President Dilma Rousseff, of Brazil.
* Mandela taught us it always seems impossible until it is done, says Obama.
"South Africa shows that is true - that we can change. We can choose a world defined not by conflict but by peace and justice.
"We will never see the likes of Nelson Mandela again."
He says Mandela's story woke him up to the struggle of others, and brought him to where he is today.
"He makes me want to be a better man," he says.
He concluded his speech by saying "God bless the memory of Madiba."
* "We remember his gestures large and small, wearing a Springbok uniform; turning his family's heartbreak into a call to tackle HIV and Aids; introducing his jailers as honoured guests at his inauguration.
He changed laws, but he also changed hearts.
For the people of South Africa, for those he inspired around the globe, his passing is rightly a time of mourning.
"But it should also prompt a time for self-reflection. With honesty, we must ask, how well have I applied his lessons in my own life? It is a question I ask myself as a man, and as a president," says Obama.
* Mandela showed us the power of action, says Obama.
The US President reads the following quote from Mandela's trial:
"I have fought against white domination and I have fought against black domination. I’ve cherished the ideal of a democratic and free society in which all people live together in harmony and with equal opportunities. It is an ideal which I hope to live for and to achieve. But if needs be, it's an ideal for which I am prepared to die."
* Obama says, "Given the sweep of his life, the admiration he so rightly earned, it's tempting to remember Mandela as an icon, smiling and serene and detached from the struggles of lesser men.
But Madiba detached himself from such a portrait, he says. "I am not a saint," he said, "Unless you think a saint is a sinner that keeps on trying."
He was a man of flesh and blood, a father and a husband, a friend.
Nothing he achieved was inevitable - he earned his place in history through persistence and faith.
* In his address Obama says, "People of every race and walk of life, the world thanks you for sharing Nelson Mandela with us. His struggle was your struggle, his triumph was your triumph. Your freedom and democracy was his cherished legacy.
"It is hard to capture in words not just the facts and the dates that make a life, but the essential truth of a person - how much harder to do so for a giant of history, who moved a nation towards justice."
* US President Barack Obama begins his speech. He is the first of five presidents to pay his tribute to Mandela.
* African Union commission chair Dr Nkosazana Dlamini Zuma says that a young Mandela understood that the struggles of the oppressed in South Africa were closely linked to those across Africa and the world. Barack Obama is up next to speak.
* Obama to speak shortly.
* Ban Ki-Moon in his condolence message says, "South Africa has lost a hero, a father, and the world has lost a friend and mentor. Nelson Mandela was more than one of the greatest leaders of our time - he was one of our greatest teachers, and taught by example. He was willing to give up everything he had for freedom and equality.He hated hatred. He showed an awesome power for forgiveness, and for connecting people with each other and with the true meaning of peace.
"That was his unique gift, and that was the lesson he shared with all human kind.He has done it again - look around this stadium. We see people from all walks of life. All are here, all are united today."
* Huge applause as Barack and Michelle Obama are shown on TV screens.
* Braving heavy rain, thousands of people flocked to the FNB stadium in Soweto to attend the memorial service of former president Nelson Mandela.
* The atmosphere in the stadium is electric and it was hard to see anyone who was sitting down or not singing.
* Security is very tight around the venue and several streets around the stadium have been cordoned off.
* Inside, bullet-proof screens have been erected around podiums where world leaders, including US President Barack Obama, will be seated.
* The delegation from India, a country that was very close to Mandela, is being led by President Pranab Mukherjee and includes Congress president Sonia Gandhi.
* The South African national anthemn was sung and then prayers said for Mandela's departed soul.
* Indian President Pranab Mukherjee, US President Barack Obama, Brazilian President Dilma Rousseff, Namibia President Hifikepunye Pohamba, Cuban President Raul Castro and China Vice-President’s Li Yuanchao to address Nelson Mandela memorial service.
* World leaders from U.S. President Barack Obama to Cuba's Raul Castro joined thousands of South Africans to honour Nelson Mandela on Tuesday in a memorial that will celebrate his gift for uniting enemies across political and racial divides.
* Obama and former president George W. Bush and their wives Michelle and Laura arrived from Pretoria's Waterkloof air base as singing, dancing South Africans made their way through heavy rain to Johannesburg's Soccer City where the homage to Mandela will be held.
* Francois Pienaar, captain of South Africa's victorious 1995 rugby World Cup-winning side, was in the stands signing T-shirts for fans of "Madiba", the clan name by which Mandela is affectionately known.
* Celebrities are also expected, including U.S. talk show host Oprah Winfrey, singers Peter Gabriel and Bono, supermodel Naomi Campbell and entrepreneur Richard Branson.
* Before the gates opened, large crowds of mourners had queued for hours to bid farewell to one of the world's most loved statesmen.
Johannesburg : South African President Jacob Zuma arrives for Nelson Mandela's memorial service pic.twitter.com/VWJu56tNxm
— ANI (@ANI_news) December 10, 2013
"I was here before 2 a.m. I did not want to miss this day. I am here to say thank you, rest in peace Madiba," said 31-year-old Amukelani Mazibuko who came from Thembia, about 80 km from the venue.
* Mandela, South Africa's first black president, died at his Johannesburg house Dec 5 at the age of 95.
"This is history in the making," Mbuyiselo Nyanda of Soweto said.
* More than 100 heads of state and government, as well as current and past presidents, will attend the memorial service. International and regional organisations will also be represented. Key dignitaries include UN Secretary General Ban Ki-moon and African Union Commission Chairwoman Nkosazana Dlamini Zuma.
"I want to be party of this crowd saying goodbye to Madiba. Go well, African hero," said another mourner Mohapi Nkoeneane.
* Nomvula Mokonyane, Gauteng province premier, said Tuesday that the provincial government beefed up free public transport with 740 extra trains to make it 5,000 in total to carry mourners to the stadium.
* The national government said over 150 public viewing sites will be open across the nation for people who cannot make it to the stadium.
* Outside the stadium, mourners sang songs in praise of Mandela, some bursting into tears.
"Nelson Mandela, Nelson Mandela Haunaye ofana niwena (Nelson Mandela, Nelson Mandela there is none like you)," they sang.
"Tata (father) was a true comrade," Amukelani Bhekisile Gaza said.
"He was a true revolutionary," 29-year-old Ncamisile Khumoyame said, as a group of young men lay on the wet ground, imitating anti-apartheid struggle veterans.
* Mandela's body will be taken from the FNB stadium to the Union Buildings in Pretoria where it will lie in state for three days, beginning Dec 11.
* From there it will be taken to Qunu in the Eastern Cape province, Mandela's native place where he would be buried Dec 15.
Here is a list of those attending the service: