By Ian Youngs
Music reporter, BBC News
Bjorn Ulvaeus (left) and Benny Andersson wrote Abba's hits
Abba duo Benny Andersson and Bjorn Ulvaeus have unveiled their first new pop songs for more than 15 years.
One track, Second Best To None, has been recorded by employees at the hotel Andersson owns in Stockholm.
It was written for the staff as a treat and has been released as a single in Sweden. "We all had some fun doing this. They can sing," Andersson said.
A second track, Story of A Heart, will appear on the first English-language album from Andersson's current band.
Andersson and Ulvaeus enjoyed huge global success as the songwriters in Abba in the 1970s and early '80s. The band's popularity has enjoyed a resurgence thanks to the hit Mamma Mia movie last year.
The pair have continued to work together over the years, including the Chess musical in the 1980s, and Andersson said their last pop collaboration was on songs for an album by singer Josefin Nilsson in the early 1990s.
"We haven't done any pop songs for a long time," the musician said.
Andersson had the idea to record Second Best To None last September at the Hotel Rival's fifth birthday party, where the workforce had gathered.
"I realised that at least 20 of them were singing in amateur choirs in Stockholm," he said. "I asked them, do you want me to write a song for you and we can put it on our homepage? They said yes so that's what I did.
"And I asked Bjorn if he would like to write the lyrics, and we recorded it with the staff. We released it as a single as well. It's just a lot of fun and it's taking care of the staff at the hotel more than anything else."
Story of A Heart, meanwhile, will feature on an album of the same name by The Benny Andersson Band.
The new track has been recorded by one of the group's vocalists, Helen Sjoholm, and will sit alongside folk tunes that have previously been released in Sweden.
Ulvaeus wrote Swedish lyrics for the originals, and has translated them into English for the UK release on 6 July.
"It's a nice prospect to be able to release music I've been doing for the last 10 years, which is folk oriented," Andersson said.
The group will also play their first English concert on Hampstead Heath on 4 July.