Stockholm, Sweden - Mamma Mia, here they go again!

It's been 40 years since the breakup of legendary Swedish pop group ABBA.

But for fans, the wait for new dancing tunes will soon be over.

"There will be new music this year, that is definite, it's not a case anymore of it might happen, it will happen," ABBA member Björn Ulvaeus (76) revealed to the Herald Sun on Saturday.

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Björn has been meeting regularly with band members Agnetha Fältskog (71), Benny Andersson (74), and Anni-Frid Lyngstad (75) at a music studio in Stockholm, where they are hard at work on new recordings.

The band became one of the best-selling musical acts of all time and split in 1982 at the height of their career. After Björn and Agnetha's divorce, their fellow couple, Benny and Frida, also saw their marriage collapse. The four performed together for the first time since at a private event in 2016, according to the Daily Mail.

The group has planned and recorded new material for an upcoming ABBAtar hologram tour to mark their 50th Anniversary, which would feature projections of themselves along with past performance footage. It has been delayed due to the pandemic.

ABBA reportedly turned down $1 billion to reunite for a reunion tour.

Now, the quartet has announced they have big plans in store for a musical reunion instead.

"The four of us stand in the studio for the first time in 40 years and there's just something in knowing what we've been through," Björn said this week. "It's hard to describe, but there are such strong, strong bonds between us."

The Swedish group first teased new music three years ago, but the tracks have never been released. Now they've said they will be adding new recordings to the upcoming five song drop.

ABBA shot to international stardom when the band won the Eurovision Song Contest with Waterloo in 1974.

Their song Dancing Queen was inducted into the Grammy Hall of Fame after becoming a worldwide chart-topper in 1976, and is still one of the most recognizable songs of all time.