They included pieces by Tracey Emin and Damien Hirst. The highest price was for The Incomplete Truth, a 2006 Hirst work consisting of a dove preserved in formaldehyde, which sold for £911,250.

The 53-year-old was a keen collector of works by the Young British Art movement and was friends with many artists.

The money raised will go to causes that the philanthropic star supported.

Another of Hirst's works - Saint Sebastian, Exquisite Pain, a representation of the death of the Christian martyr using a bull encased in formaldehyde - sold for £875,250 at the London auction.

The Incomplete Truth by Damien Hirst alongside other works from George Michael's collection

Bridget Riley's 1982 painting Songbird, the first major work Michael acquired, fetched £791,250, while Hurricane, a 2007 work by Emin, sold for £431,250.

Other lots sold on Thursday included three works by Michael Craig-Martin that reference Michael's 1998 notorious arrest for engaging in a sexual act in a public toilet. Untitled (SEX), Untitled (GOD) and Handcuffs sold for £125,000, £40,000 and £112,500 respectively.

A life-size bronze gorilla by Angus Fairhurst that used to sit in Michael's garden also went under the hammer, fetching £118,750.

 Works by Angus Fairhurst and Bridget Riley were also sold on Thursday

According to Cristian Albu from Christie's, Michael's "most intense" period of art-buying took place between 2004 and 2009.

"I'm sure he had advisors but I think he pleased himself and made up his own mind what he liked," Albu told the BBC's Vincent Dowd earlier this month.

Christie's attributed the fact every lot sold on Thursday to both Michael's "eye for contemporary art" and "the depth of feeling" he continued to generate.