Dr Singh paid tributes to the late South African leader who, passed away on Friday last.
"A giant among men has passed away. In the demise of Dr Nelson Mandela, South Africa and India have lost a great Gandhian of our age. May his soul rest in peace," he wrote in the condolence book at the Mission.
The Prime Minister had earlier hailed Mandela as a beacon of hope for those struggling against oppression and injustice and said his passing away is as much a loss to India and the world as it is to South Africa.
Dr Singh had noted that Mandela not only represented the conscience of the world, he also remained a beacon of hope for those struggling against oppression and injustice long after he had led his own people to victory over such ills.
"Nelson Mandela endured great personal hardship so that others could be provided with dignity, equality and opportunity. He fought discrimination and inhuman exclusion, but rose above bitter divisions to heal and reconcile a fractured nation. His life and work made him a citizen of the world," he said.
"India, in particular, had great affection and regard for him. His mission was a great inspiration and moral bulwark for our principled struggle against apartheid. It also mirrored our own hope for a better world and we were greatly honoured when he accepted the highest Indian civilian award of Bharat Ratna," the Prime Minister said.
He said India joins South Africa and the world in mourning his loss. "But we know that his life and ideals will inspire generations to come. May God bless his soul," Dr Singh said.