Pop group Abba have returned to the studio to record their first new music since the 1980s.
The Swedish quartet said the new material was an "unexpected consequence" of their recent decision to put together a "virtual reality" tour, says a BBC report on Friday.
"We all four felt that, after some 35 years, it could be fun to join forces again and go into the studio," the band said on Instagram.
"And it was like time stood still."
No release date has been set for the new songs - but one of them, titled I Still Have Faith In You, will be performed in December on a TV special broadcast by the BBC and NBC.
Abba's spokesperson Gorel Hanser described the new songs, saying: "The sound will be familiar, but also modern."
The studio sessions were "like old times", she told Swedish newspaper Aftonbladet.
"Easy as anything. It didn't feel weird that they hadn't been in the studio together for 35 years."
But Hanser said the group would not perform live, other than as holograms in the forthcoming Abba Avatar tour.
"No, you cannot expect them to join forces on stage again," she said. "They will not do that."
The band have resisted pressure to reform since they stopped recording together in 1982, despite a reported $1 billion (£689 million) offer for to tour in 2000.