British Prime Minister David Cameron on Thursday said "a great light had gone out" following Nelson Mandela's death, revealing that flags would be flown at half-mast at his Downing Street Office.
"A great light has gone out in the world," Cameron wrote on his official Twitter account.
"Nelson Mandela was a hero of our time. I've asked for the flag at No.10 to be flown at half mast."
US President Barack Obama paid tribute to the anti-apartheid icon, saying the world would likely not see the likes of him again.
"He achieved more than could be expected of any man, and today he's gone home," he said.
"He no longer belongs to us, he belongs to the ages."
Former Australian Prime Minister Julia Gillard was among the first to comment after news broke of his passing.
"The world has lost a great man," she said via Twitter.
"As we grieve for Nelson Mandela we should also celebrate his tremendous victory over prejudice and hate."
Prime Minister Tony Abbott called Mr Mandela "one of the great figures of Africa, arguably one of the great figures of the last century," speaking to Fairfax radio this morning.
He was the father of modern South Africa, he said.
"A truly great man.
"And while I never met him I did read that book A Long Walk To Freedom and I guess the impression we get of Nelson Mandela is someone who suffered but was not embittered but ennobled through that suffering."
What they said: World leaders past and present react to news that Nelson Mandela has died
"A great light has gone out in the world." - British Prime Minister David Cameron
"The world has lost one of its great moral leaders." - Canadian Prime Minister Stephen Harper
"As we grieve for Nelson Mandela we should also celebrate his tremendous victory over prejudice and hate." - Former Australian Prime Minister Julia Gillard.
"He no longer belongs to us, he belongs to the ages." - US President Barack Obama.
"Madiba passes on- but what is certain he will continue to live in the hearts of many of us." - President of the Republic of Rwanda, Paul Kagame
"The world has lost one of its great citizens." - President of Tanzania, Jakaya Kikwete
"He will always be remembered for what he gave the world. Human dignity." - Amama Mbabazi, Ugandan Prime Minister
