German Prince Ruzzo Reuss von Plauen died aged 49 with 53-year-old Anni-Frid at his side. The funeral will take place on 11 November.

The couple married in Denmark in 1992 and lived at Ruzzo's castle in Switzerland.

Ruzzo grew up in Rome but spent the summers with his Swedish mother Louise.

His title was inherited from his father Enzio. The family ruled the Reuss sovereignty in the former East Germany up until 1918.

Ruzzo leaves twin daughters Henriette and Pauline from his first marriage to a Norwegian ship-owner's daughter.

Frida with her former husband Benny in their Abba heyday

It's not the first time that Swedish pop veteran Anni-Frid's life has been touched by tragedy.

Two years ago her daughter, Ann Lise-Lotte Casper, was killed in a traffic accident in the US aged 30.

Anni-Frid had been married twice before - first to her childhood love Ragnar Fredriksson and famously to her bandmate Benny Andersson in 1978.

A grandmother and staunch ecological campaigner, Anni-Frid was reported to be too busy nursing Ruzzo for the opening night of the Abba musical Mamma Mia! when opened last April at London's Prince Edward Theatre

She has, however, maintained a recording career. Recently she was back in the Swedish charts with a duet, Wonderful World, with Marie Frederiksson of the duo Roxette.