ABBA have led tributes to their sound engineer, Michael B. Tretow, who has died aged 80.

News of the Swedish record producer's passing was confirmed to the Swedish publication Aftonbladet.

ABBA's manager Görel Hanser confirmed the sad news. No cause of death is known at this time.

After being chosen by Björn Ulvaeus and Benny Andersson to be their sound engineer in 1970, Michael worked on all of the 'Waterloo' hitmakers' albums except for 2021's 'Voyage'.

In a touching tribute, Benny Andersson told the outlet: "You meant more to us four in ABBA than anyone else.

"I hope and believe that you felt it throughout all the years that have passed since we worked (and continuously laughed) in the studio.

"Our music lives on, it seems, and you are the one who made it timeless. You were a fantastic inspirer and joy-maker, and the finest sound engineer the world has ever seen.

"I miss you. And I've saved all your coconuts!"

Björn Ulvaeus said the way he shaped the Eurovision-winning band's sound "cannot be overestimated".

Anni-Frid Lyngstad said: "No one fit the bill as well as you.

"For us, you are forever part of the ABBA sound and you will never be forgotten."

Fourth band member, Agnetha Fältskog, recalled spending time with Michael just recently.

She reflected: "So glad I got to spend some time with you a few weeks ago… You were so sick, but your laughter and humour were still there.

"So many memories are preserved, your encouraging words during the recordings meant so much. We are sad now, a talented and unique person has left us. Sleep well Micke, you are in our hearts forever."