He took to Twitter to pay his respects, writing: "Time goes by so quickly. It's not that long ago we spent days and nights in my tiny apartment in Halmstad, listening to music we loved, sharing impossible dreams. And what a dream we eventually got to share!"

Marie was diagnosed with a brain tumour in 2002 and took a break from performing on doctors' advice but she made a recovery from the condition in 2009 and returned to the stage with Roxette.

However, her illness returned in 2016 and Marie - who also released several solo albums throughout her career - permanently gave up touring.

The duo enjoyed huge pop success in the 80s and early 90s with singles such as 'The Look', 'Joyride' and 'Dressed For Success'.

Power ballad 'It Must Have Been Love' featured in 1990 movie, 'Pretty Woman' which starred Julia Roberts and Richard Gere, making Roxette household names all over the world.

Per praised the late Swedish singer for her beautiful talent that turned his "black and white songs" into chart-topping hits.

He continued: "Thank you, Marie, thanks for everything. You were an outstanding musician, a master of the voice, an amazing performer. Thanks for painting my black and white songs in the most beautiful colours. You were the most wonderful friend for over 40 years. I'm proud, honoured and happy to have been able to share so much of your time, talent, warmth, generosity and sense of humour. All my love goes out to you and your family. Things will never be the same."