British pop star Robbie Williams and US group The Black Eyed Peas will join Ariana Grande at Sunday's charity concert in Manchester for families of the victims of last week's terror attack, organisers said.
The "One Love Manchester" gig at the city's Old Trafford cricket ground has already attracted a stellar line-up including Katy Perry, Coldplay, Justin Bieber, Pharrell Williams, Miley Cyrus, Take That, Usher, Little Mix and One Direction's Niall Horan.
The concert will honour the 22 people killed -- many of them children -- and the 116 wounded in the suicide bomb attack at the end of Grande's show at the Manchester Arena on May 22.
Manchester-born Salman Abedi, a 22-year-old of Libyan origin, was named as the bomber.
Police on Thursday released new images of Abedi, calling for the public's help in tracking his movements in the days leading up to the attack.
"What we still need to understand is if he had any of the bomb parts in his possession before he went out of the country, this is why we're tracking his movements so carefully," it said in a statement.
Proceeds from the Sunday's concert will go to a fund set up to help the victims' families. The attack shook the country and led to the temporary suspension of a general election campaign.
Performances at the 50,000 capacity stadium will kick off at 7.15pm (1815 GMT) and will be streamed online and broadcast by the BBC.
Tickets went on sale Thursday, selling out within six minutes, with website Ticketmaster reporting "incredible" demand.
Organisers have announced that anyone present at last month's deadly concert will be able to attend the tribute concert for free.
A spokeswoman for Ticketmaster said that "over 10,000 unscrupulous applications" had been made on Thursday, with people applying for free tickets despite not attending the original concert.
The ticket operator had set aside 14,200 tickets for those at the May 22 show, but received more than 25,000 applications.
Ticketmaster said it was also cancelling tickets of people who were reselling them.
"At Ticketmaster we are doing everything we can - including extending today's deadline -- to ensure that tickets go to the actual fans and not the opportunists or touts who have also been applying for free tickets," the company said.
Several secondary ticketing sites such as Stubhub and Viagogo have pledged to not allow the reselling of tickets for the concert on their websites.
Grande, who said that she was "broken" by the atrocity, returned to her home in Boca Raton, Florida, the day after the attack.
The 23-year-old Grande cancelled dates on her "Dangerous Woman Tour" until June 7, and called on her fans to "come closer together, to help each other, to love more, to sing louder and to live more kindly and generously than we did before".