Madonna's friends' tragic deaths inspired her to become an AIDS activist

It included paying for British artist Martin Burgoyne's medication before he died aged 23 in 1986 and convincing her then-husband Sean Penn to jet out to Mexico to buy a drug that was thought to possibly cure the disease.

Madonna was quoted by The Times saying about her pal's death: "What could I do? I loved him. And people with Aids are treated like they're lepers or something.

"If they contract Aids, all their friends disappear.

"That's not a friend. How could I desert him? He was really my best friend."

Martin introduced the 'Cherish' hitmaker to the New York club scene after they met at a club in East Village where he worked as a bartender.

They later shared an apartment, and he went on to manage her first club tour and design the 'Burning Up' single cover in 1983.

In the unearthed tapes from Madonna's brother - which are going to be used as part of a 90-minute Sky documentary called 'Becoming Madonna' - Christopher remembered his sister putting on the 1987 'Who's That Girl?' tour in memory of Martin, and generating $400,000 for the American Foundation for Aids Research.

He was quoted by The Times saying: "The AIDS benefit that we did at Madison Square Garden was emotionally taxing for everybody.

"Especially for [Madonna], because of Martin. There had been so many friends of ours who had Aids."

Christopher - who also directed videos for Tony Bennett and Dolly Parton, as well as working as an interior designer - fell out with his superstar sibling when he released his 2008 best-selling book 'Life With My Sister Madonna'.

The two eventually reconciled, and in 2012, Christopher released his own footwear line.

After the 63-year-old visual artist's death - which came just a few weeks after Madonna's stepmother Joan Ciccone died from a "very aggressive cancer" - she said: "He had impeccable taste and a sharp tongue which he sometimes used against me.

"But I always forgave him."