Thank You For The Musical: ABBA foursome together again

It was a reunion 22 years in the making as all four members of the Swedish pop group ABBA appeared for the first time together in public at a movie premiere of Mamma Mia! in Stockholm.

Benny Andersson, Bjorn Ulvaeus, Anni-Frid Lyngstad (Frida) and Agnetha Faltskog walked down the red carpet on Friday evening to the cheers of several thousand fans.

The foursome last performed together in public in 1986 and have resisted calls and massive offers of money to do a reunion tour.

Andersson and Ulvaeus are the brains behind the Mamma Mia! musical, which features 22 ABBA songs including Thank You For The Music, Take a Chance on Me, Dancing Queen, The Winner Takes It All, Voulez Vous and I Have A Dream.

First launched in London in 1999, the musical has since been staged around the world.

The film adaptation stars Meryl Streep in the title role of a former hippie whose 19-year-old daughter decides to search for her biological father among her mother's three former flames played by Colin Firth, Pierce Brosnan and Stellan Skarsgard.

"Most of them don't think they can sing," said Ulvaeus about the actors. "But they can, I assure you."

Streep embraced Lyngstad and Faltskog on the red carpet. The four ABBA members appeared in the theatre balcony and then stood together with cast members after the screening.

Streep said she was excited by being able to sing in a movie, recalling that she used to perform in high school musicals.

"It was kind of like coming home to the thing that I loved very, very much," the 59-year-old actress told Reuters. Streep also said she doesn't have just one favourite ABBA song.

The actors said the hardest part about playing their characters was doing it in spandex.

"You're going to get bulges that you didn't want and not really developments you did want," admitted Firth, star of the Bridget Jones movies.

The film is set for release in North America July 18.