A website titled 'Mamma Mia! The party' emerged last week, with Swedish music composer Ulvaeus writing he had created a “new entertainment experiment that I will tell everyone about on Wednesday”.

Another message sent to Abba fans across the globe, signed by Ulvaeus, said: “I've been working on this experiment for quite a while now and it's actually starting to feel ready.”

The project's PR agents refused to tell The Local more when prompted. But the secrecy has not stopped fans from speculating. After all, a potential Abba reunion – which several of its former members have hinted at in the past – has been high on the list of fans' hopes ever since the group split up in the 1980s.

Got a letter from Björn Ulvaeus, I never thought that would happen when I was 10 years old Mamma Mia The Party: http://t.co/vskAdtkkYe

— kirsty elliott (@kirstita) April 11, 2015

Oh, the suspense! #björnulvaeus http://t.co/a8lbep7LtI #mammamiatheparty #mammamia #abba

— Karen Freedman (@Karen_Freedman) April 10, 2015

“I doubt it will be a reunion – and most serious fans would agree that will not happen. There has been a suggestion of a Mamma Mia themed dinner party for 100 people and then a performance. Sounds like fun, but only for the 100. I think we all hope it will be something all fans can enjoy – not just a select few,” Australian Abba fan Roxanne Dickson told The Local on Tuesday.

“Someone did suggest it could be a global Skype dinner party – can't imagine that would be it though!” she added.

Like many Abba fans, she remains emotional when talking about the group.

“I have been an Abba fan since 1975. They got under our skin, in our hearts and never left – impossible to say why. They were simply perfection and affected people of all ages. They were different, and had mass appeal. No other group ever affected me the way Abba did,” said Dickson.

Abba was formed by Björn Ulvaeus, Benny Andersson, Agnetha Fältskog and Anni-Frid 'Frida' Lyngstad in Stockholm in 1972. After winning the Eurovision Song Contest two years later with mega hit 'Waterloo', the band went on to become one of the most commercially successful acts in the history of pop music.

After the group's break-up, Fältskog and Lyngstad pursued solo careers with mixed success. Andersson and Ulvaeus went on to write music for the stage, including hit musical 'Mamma Mia!', which was turned into a feature film starring Meryl Streep and Sweden's own Stellan Skarsgård in 2008.