Bjorn Ulvaeus, left, and Benny Andersson are seen at a screening of the movie Mamma Mia at the American Film Festival in Deauville, France, last September. (Michel Spingler/Associated Press)

Benny Andersson and Bjorn Ulvaeus, the writing talent behind the 1970s supergroup Abba, are a pop partnership again — producing the first new tracks they've written together in more than 15 years.

Second Best to None, which has been released as a single in Sweden, was written for the staff at the Hotel Rival, the Stockholm hotel that Andersson owns. It is performed by the hotel staff, many of whom sing in amateur choirs in Stockholm.

Story of a Heart will be released as the title track of an upcoming album by the Benny Andersson Band, which features songs inspired by Swedish folk music. Ulvaeus wrote the song's Swedish lyrics and translated them into English for the album's release in Britain on July 6. Helen Sjoholm, one of the group's vocalists, sings the song.

"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 told BBC News.

Andersson and Ulvaeus's first names represent the two Bs in the middle of ABBA. They formed the group with Agnetha Faltskog and Anni-Frid Lyngstad, whose first names represent the two As.

Abba sold more than 370 million records worldwide. Famous for hits such as Waterloo and Dancing Queen, the group's music has enjoyed a resurgence in popularity thanks to the hit movie Mamma Mia last year.