Adam Cox

The super troupers of 70s pop were back in force last night. All four members of Abba appeared together at the Swedish premiere of the film Mamma Mia!, delighting fans with their first public showing for years.

Benny Andersson, Bjorn Ulvaeus, Anni-Frid Lyngstad - known as Frida - and Agnetha Faltskog walked down the red carpet at a Stockholm movie theatre to the cheers of several thousand fans.

The movie follows Mamma Mia! the musical, which toured worldwide and features 22 Abba songs, including Dancing Queen, Take a Chance on Me and The Winner Takes It All.

The foursome, who shot to fame when they won the 1974 Eurovision Song Contest, last performed together in public in 1986.

At the film premiere, Agnetha and Frida embraced with actress Meryl Streep, posing for pictures before the three did a dance together. Moments later, all four band members appeared on the theatre balcony.

They stood together with Streep, Pierce Brosnan, Colin Firth and other members of the Mamma Mia! cast. Streep, Brosnan and Firth enthused about Abba's music while discussing the challenges of singing and wearing figure-hugging Spandex costumes.

"Once I started singing I kind of rather enjoyed it," Brosnan said. "The Spandex was a bit of a challenge. But I had the time of my life."

Co-star Firth, star of two Bridget Jones's Diary films, said the most frightening aspects of the film were also the most motivating. "There's an old Miles Davis quote which I've always cherished, which is Don't play what you know, play what you don't know'," Firth said.

The Spandex outfits were a different matter. "You're going to get bulges that you didn't want," said Firth.

Ulvaeus had high praise for the actors' vocal abilities. "Most of them don't think they can sing, but they can."