Robbie Williams has been added to the star-studded line-up of Simon Cowell's charity single for the Grenfell Tower fire.

Reportedly due to the ever-growing guest list, Cowell's orchestrated cover of Simon And Garfunkel's Bridge Over Troubled Water will be released on Wednesday 21 June at 8am. It was initially expected to arrive on Monday 19 June.

Confirming the news, Good Morning Britain journalist Philippa Tomson tweeted: "Robbie Williams, Emeli Sande. Some of the stars recording the Artists For Grenfell single. Released on Wed. More on @gmb MON." The reporter claims to have heard the song and said it is "sounding incredible".

It comes after several stars were seen arriving at the Sarm recording studios in Notting Hill, west London, nearby to where the blaze at Grenfell Tower took place on 13 June.

Rita Ora led the way with the likes of Leona Lewis, James Blunt, Roger Daltrey, Craig David, Pixie Lott, Stormzy, Westlife's Shane Filan, Gregory Porter and Emeli Sande, following behind. Other musicians confirmed to appear on the charity cover, include Paloma Faith, Ella Eyre, Tulisa Contostavlos and Skepta.

Speculation is rife that One Direction will reunite on the ballad with Louis Tomlinson and Liam Payne confirmed to appear. Band members Harry Styles and Niall Horan are yet to announce their involvement but a source told The Sun that if all four singers appear on the charity song, it would be as solo acts rather than the group.

Robbie Williams
Simon Cowell
Robbie Williams joins the star-studded guest list on Simon Cowell's charity single for the Grenfell Tower victims

Led by choir singer Gareth Malone, around 300 locals from north Kensington, some of whom are said to be survivors of the tower block fire, have also joined the celebrity line-up.

Prime Minister Theresa May has agreed to waive the VAT on the single release, with profits going towards victims of the tragedy, which has claimed at least 58 lives so far. Announcing his plans for the charity single, Cowell tweeted: "I am watching the footage of the Grenfell Tower fire in London. Heartbreaking. We hope to confirm a record tomorrow which will raise some money for the many people affected by this tragedy. Making calls tonight."

Listen to Simon And Garfunkel's Bridge Over Troubled Water: