The band has recorded two new songs, one of which is titled, I Still Have Faith In You.
A statement on the band's official Instagram account said: "The decision to go ahead with the exciting Abba avatar tour project had an unexpected consequence.
"We all four felt that, after some 35 years, it could be fun to join forces again and go into the recording studio. So we did. And it was like time had stood still and that we had only been away on a short holiday. An extremely joyous experience!
"It resulted in two new songs and one of them, I Still Have Faith In You will be performed by or digital selves in a TV special produced by NBC and the BBC aimed for broadcasting in December.
The statement added: "We may have come of age, but the song is new. And it feels good."