Göteborg, Sweden - Lasse Wellander, the long-time guitarist of the legendary Swedish pop band ABBA, has died at the age of 70, according to a report.

The musician died on Friday, according to a report in the Swedish newspaper Göteborgs-Posten on Sunday evening, citing family members.

Relatives of the guitarist posted on Wellander's Facebook page that the musician had died of cancer in his sleep, surrounded by his loved ones.

"It is with indescribable sadness that we have to announce that our beloved Lasse has fallen asleep. Lasse recently fell ill in what turned out to be spread cancer and early on Good Friday he passed away," the post said in Swedish.

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He was an outstanding musician, but above all "a wonderful husband, father, brother, uncle and grandfather, and so much more that cannot be put into words," they said in the post.

A statement to the PA news agency from Abba band members Bjorn Ulvaeus, Benny Andersson, Agnetha Faltskog, and Anni-Frid Lyngstad said: "Lasse was a dear friend, a fun guy and a superb guitarist."

"The importance of his creative input in the recording studio as well as his rock solid guitar work on stage was immense."

"We mourn his tragic and premature death and remember the kind words, the sense of humor, the smiling face, the musical brilliance of the man who played such an integral role in the Abba story."

"He will be deeply missed and never forgotten."

Göteborgs-Posten said Wellander was born in 1952 and began his career as a professional musician as a teenager.

He accompanied the ABBA on several albums – including the comeback record released in 2021 – and tours from the 1970s onwards, as the hit act made waves across the world.

He also contributed to the soundtracks of the incredibly successful Mamma Mia films.

Alongside ABBA, he also played with other Swedish artists such as Pugh Rogefeldt and Ted Gärdestad.