The Irish boy band had been booked to appear on the opening night of the festival, Friday, June 18, but their plans were put on hold following the death of band member Stephen Gately in Majorca last month, aged 33.

Festival promoter Jonathan Irving said if the band decide they do want to go ahead with their performance, he will extend the festival by one night and they can play on Thursday, June 17.

On Friday, Mr Irving revealed JLS, with special guests, will now be headlining the Friday night of the festival, while Calvin Harris will be the main support act the following night.

Mr Irving said former X Factor contestants JLS are the hottest band in the whole of Britain right now.

Their newly-released single, Everybody in Love, shot straight to number one on the downloads chart this week, selling twice as many copies as Cheryl Cole's Fight For This Love.

Pre-sales of their debut album, JLS, which was released yesterday (Monday), have already topped more than 200,000 copies.

The talk is they will have sold more than one million albums by Christmas.

Mr Irving said: 'JLS won Best Newcomer award at the 2009 MOBOs and then went on to scoop up the Best Song.

'We are unbelievably excited to have signed them for the Manx Telecom Bay Festival 2010 and they will be performing a full production show, complete with backing dancers, stunning light show, special stage effects and video screens – in fact, just like their spell binding performance on the X Factor last Sunday, which they took by storm.'

JLS also won the BRIT award this year for the Best British Single.

Tickets for JLS at the Manx Telecom Bay Festival are available for pre-sales today (Tuesday) and general sale from tomorrow. To book visit www.bayfestival.im or ring the call centre on 600600.

Meanwhile, Calvin Harris will appear at the festival on Saturday, June 19.

His second studio album, Ready for the Weekend, was released in August and reached number 1 in the UK Album Charts.

Tickets will not go on sale for the highly-acclaimed electronic musician, singer-songwriter and record producer's appearance until the headline artist is announced.

The festival will take place in Noble's Park, Douglas, from June 18 to 20. The final day will see an X Factor meets Britain's Got Talent event in the afternoon and a Last Night In the Park – 80s Stonkin' Party, featuring Rick Astley and Boy George, among others, in the evening.