Relations between George Michael and Sir Elton John were once so bad that George told Sir Elton to shut his mouth and stop interfering in his life.

But any acrimony between the two pop stars was clearly behind them when George took to the stage to perform a cover of an Elton John song - while the artist himself watched from the audience.

At a special gig by the former Wham! singer to raise money for Aids charities, Michael told the star-studded audience he hoped the Idol singer was among them.

Introducing his cover of the song at the Royal Opera House in London, he said: "This next song was written by someone I hope has made it in here already - Elton. It's a song he wrote in the late 70s and it's about an ageing pop star. Funny that."

As George cast his gaze around the audience, Sir Elton waved from the stalls, where he sat beside his civil partner David Furnish and broadcaster Janet Street Porter. Little Britain star David Walliams sat beside Janet with his wife Lara Stone.

Other celebrities present at the black tie event - which formed part of George's 47-date Symphonica tour of Europe - included Kylie Minogue, comedian Michael McIntyre and actor James Corden.

George singled out Corden, with whom he performed a Comic Relief sketch this year in which the Gavin And Stacey star cried: "You're a joke, George. It's embarrassing."

The singer told the audience: "My manager read the script and said 'you can't have him say that.' I said 'that's the whole point. I want him to say that.'"

Michael's gig raised a total of £987,000 for the Elizabeth Taylor Memorial Fund, his publicist said.