Abba's greatest hits collection has overtaken The Beatles' Sgt. Pepper in the chart of the biggest selling albums in British musical history.
An estimated one in five British households owns a copy of either Gold or Sgt Pepper's.
The announcement coincides with this year's Eurovision Song Contest being held in Abba's homeland. The group won Eurovision in 1974 with Waterloo, which became their first number one single in the UK.
Bjorn Ulvaeus, who co-wrote Abba hits including Dancing Queen, Knowing Me Knowing You and The Name Of The Game said: “It feels unreal - outselling the greatest record of all time.”
Queen's 1981 Greatest Hits album remains the UK's most popular, with 5.9 million sales.
Adele's 2011 album, 21, and Oasis' 1995 second album, (What's the Story) Morning Glory?, complete the top 5.
This week may also mark a double celebration for Abba, with the group's former singer Agnetha Faltskog looking set to score the highest-charting solo album of her career this evening.
Her new offering, A, looks likely to break the top 10 according to mid-week sales figures, while her previous UK best, My Colouring Book, peaked at Number 12.