Rocker and activist Bono has come to cherish his unlikely friendship with former U.S. President George W. Bush after working together to fight the HIV/AIDS epidemic in Africa.

The U2 frontman, who is known for his liberal views, famously paid a visit to the White House in 2002 to try and convince the Republican leader to join the global push for action, leading Bush to launch the groundbreaking programme PEPFAR (President's Emergency Plan for AIDS Relief) in 2003.

The initiative has been credited with saving more than 16 million lives to date, and against all odds, Bono and Bush have formed a close bond.

As the singer prepared to mark World AIDS Day on Saturday (01Dec18), he sat down with the Texan politician's daughter, TV co-host Jenna Bush Hager, to reminisce about their tense first meeting 16 years ago.

"He didn't wanna see me, which is fair enough, I mean, different political views and whatever," the Irish musician shared on U.S. breakfast show Today.

"I was the guy who had to come... and get him to look up from his big oak table in the Oval Office to let his values tell him what to do," he remembered. "I don't know if it's a Texas thing, but your father felt the weight of responsibility presiding over this, the greatest health crisis in 600 years, (to take action)."

Bono has never shied away from heaping praise on Bush for establishing PEPFAR, declaring the period "one of the most heroic chapters in the history of America," and he wants world leaders and activists today to learn from their odd partnership.

"I think you gotta cut through the shenanigans of political cartooning and see that some people can have different views and can still be principled people...," he said.

"I hope Americans this World AIDS Day remember what you can achieve when you work with people you don't agree with."

The pair has remained in touch over the years, and Bono is particularly enamoured by Bush's sense of humour.

"I have this kind of comedic relationship with your father," he smiled as he remembered one particular funny exchange.

"We were riding in a motorcade. People were waving from the side of the road, and I said to him, 'Oh, pretty popular. Didn't think you were this popular, Mr. President!' He said, 'When I first came here, they used to wave at me with one finger!'

"I've become very fond of him, and it's funny because underneath his armour, there's passion, compassion; he has it."