Abba have announced their first album in 39 years and debuted two new songs in a long-anticipated comeback.
The Swedish band - Bjorn Ulvaeus, Agnetha Faltskog, Benny Andersson and Anni-Frid Lyngstad - also unveiled plans for a high-tech concert show featuring digital versions of themselves.
Both projects will be titled Abba Voyage and the album will consist entirely of new material recorded by the quartet, known for hits such as Dancing Queen, Super Trouper and Waterloo, in Andersson's studio in Stockholm.
The tracks, I Still Have Faith In You and Don't Shut Me Down, were played publicly for the first time during a press conference at the top of the Orbit sculpture at Queen Elizabeth Olympic Park in east London, which was also livestreamed to fans.
Attending in person, Ulvaeus and Andersson told how the album had emerged after the quartet reunited to film the digital concert.
Their last album of new material, titled The Visitors, was released in November 1981 and they parted ways soon after, despite never officially splitting up.
Last month the band sparked excitement among fans as they launched a website called Abba Voyage, which asked fans to register on the landing page and teased: "The wait is nearly over..." and on Monday they joined social media site TikTok.
The pop group were catapulted to worldwide success after winning the Eurovision Song Contest with Waterloo when the event was held in Brighton in 1974.
They have since sold more than 400 million albums and singles.
The popular quartet parted ways after last performing together in 1982 following a successful 10-year stint.
In 2018 they announced they had recorded new material, but the release of the songs has been delayed.
The musical Mamma Mia!, based on their songs, premiered in London in 1999 and became a worldwide hit.
Two movie versions - Mamma Mia! and Mamma Mia! Here We Go Again - pulled in an A-list cast including Meryl Streep, Dame Julie Walters, Colin Firth and Pierce Brosnan.