It must feel like the 1970s again for Abba fans as the iconic pop group have reunited for the first time in more than 30 years. Agnetha Faltskog, Björn Ulvaeus, Benny Andersson and Anni-Frid "Frida" Lyngstad shared the stage once again in Stockholm on 6 June to celebrate their 50th anniversary and admit they were "emotional" after their long-awaited reunion.

Abba songwriters Andersson, 69, and Ulvaeus, 71, hosted the private party at the Berns Salonger hotel to celebrate half a century since the quartet met for the first time. Despite years of brushing off the possibility of a reunion, Faltskog and Lyngstad graced the stage to duet on their 1980 song Me And I for which they were joined by their songwriting former husbands.

Speaking to the press after the impromptu performance, Lyngstad said: "It's been a great night. It was absolutely amazing. A lot of emotions. We've made this journey throughout our history. Benny and Bjorn in particular. It's been very nostalgic." It is now the second time Abba have reunited publicly in 2016 following their appearance at the launch of Mamma Mia! The Party in Stockholm in January.

Adding to the nostalgia, the evening was compered by radio DJ Claes af Geijerstam, a member of the group Ola & The Janglers who beat Abba to represent Sweden at the Eurovision Song Contest in 1973. However, Abba took the honour the following year and won with Waterloo which went on to become one of their biggest hits. The four-piece have sold more than 380 million albums worldwide and are known for singles such as Dancing Queen, Mamma Mia, Knowing Me Knowing You and The Winner Takes It All.

ABBA. #björnobenny #b&b50 #thankyouforthemusic

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Shutting down rumours that Abba would one day reform, Ulvaeus told Billboard in 2014: "We took a break in '82, and it was meant to be a break. It's still a break and will remain so. You'll never see us on stage again."

The singer also told the Mail On Sunday in 2013: "I promise you, Abba, will never reform – I couldn't bear the stress of disappointing everyone. And when you listen to our music, isn't there something good in having the image of four young, energetic people? Better than four geriatrics, that is for sure." At one point, rumours claimed Abba had turned down an offer of $1bn (£685m) to perform on a reunion tour and sign a new record deal but this has never been confirmed.

Abba, consisting of Benny Andersson, Anni-Frid Lyngstad, Agnetha Faltskog and Bjorn Ulvaeus, split in 1982 AFP/Getty