Departing US President Barack Obama has paid tribute to his "brother" Joe Biden in his farewell speech.

The pair's partnership has been so close it spawned a wave of internet memes, while First Lady Michelle Obama has said her husband views the Vice-President "like the big brother, somebody he respects and admires".

Mr Obama praised Mr Biden in Chicago last night and called him "the scrappy kid from Scranton who became Delaware's favourite son".

He said: "You were the first decision I made as a nominee and it was the best.

"Not just because you have been a great Vice-President, but because in the bargain I gained a brother. We love you and Jill like family and your friendship has been one of the great joys of our life."

In his final curtain call, Mr Obama grew more emotional when he gave thanks to his wife, Michelle and daughters Malia and Sasha, to his staffers, and to Mr Biden.

When the first black president of the United States left the stage, he assured Americans, his supporters, and the many marginalised people to whom he has devoted his entire political career that began in Chicago that his work was not done – and neither was theirs.

“My fellow Americans, it has been the honour of my life to serve you,” he said. “I won’t stop; in fact, I will be right there with you, as a citizen, for all my remaining days. …

“But for now, whether you are young or whether you’re young at heart, I do have one final ask of you as your president — the same thing I asked when you took a chance on me eight years ago.