"Death is inevitable. When a man has done what he considered to be his duty to his people and his country, he can rest in peace. I think I have made that effort, that's why I slept- Nelson Mandela

Nelson Mandela, whose victory against apartheid united his native South Africa and changed the course of modern history, has died following a long illness.

The Nobel Peace laureate, who spent nearly three decades as a political prisoner before going on to lead his country, passed away at his Johannesburg home surrounded by his family.

South African President Jacob Zuma said "the nation has lost its greatest son", adding "he is now resting. He is now at peace".

Mr Mandela, who was 95, will get a state funeral and

national flags will be lowered to half mast, said Mr Zuma.

Mr Mandela had been receiving medical treatment for the last three years for a prolonged lung infection and for the last six months had been critically ill.

"Our people have lost a father," said Mr Zuma.

"Although we knew this day was going to come, nothing can diminish our sense of a profound and enduring loss.

"His tireless struggle for freedom earned him the respect of the world. His humility, passion and humanity, earned him their love."

The anti-apartheid icon served as South Africa's first black president from 1994 to 1999 after spending 27 years in the notorious Robben Island prison.

Madiba - as he was affectionately known by many South Africans - was released in 1990 and went on to guide his country to democracy, bringing an end to white minority rule and securing black people the right to vote.

UK Prime Minister David Cameron, speaking outside Downing Street, said: "Tonight one of the brightest lights of our world has gone out.

"Nelson Mandela was not just a hero of our time, but a hero of all time.

"Through his dignity, through his triumph, (he) inspired millions."

"He achieved more than can be expected of any man - and today he's gone home," said President Obama.

"We've lost one of the most influential, courageous and profoundly good human beings that any of us will share time with on this earth."

"He no longer belongs to us - he belongs to the ages."

Prince William, who was attending the London premiere of a film about Mr Mandela's life when the news broke, also paid tribute.

"It was extremely sad and tragic news," he said.

"We were just reminded of what an extraordinary and inspiring man Nelson Mandela was and my thoughts and prayers are with him and his family right now."

Crowds have gathered outside Mr Mandela's Johannesburg home singing songs in celebration of his life.

Sky News' Alex Crawford, who is at the scene, said people were dancing and clapping.

"People are upset," she said. "They've come with flowers, people are obviously very emotional about it, but they are also in a very celebratory mood as well.

"It was very sombre when we arrived (but) more and more people have gathered here and the mood is entirely different.

"It has changed to singing tribute songs, they've sung the national anthem, they're singing a lot of songs from way back when they were pushing for democratic rights.''