The 28-year-old midfielder fell unconscious in his own home last week and was taken to Aarhus University Hospital, the club said in a statement.

“Kristoffer Olsson is suffering from an apparently acute brain-related illness that is not due to self-harm of any kind, nor is it caused by external factors,” Midtjylland said.

Olsson has remained unconscious and an exact diagnosis has not been communicated.

Hailing from Norrkoping on Sweden’s east coast, Olsson made his competitive debut for Arsenal in 2013, and has since played for Danish side Midtjylland and AIK in Sweden, then Krasnodar and Anderlecht, before rejoining Midtjylland.

The Swedish Football Association wished Olsson – who plays for Sweden’s national squad – a speedy recovery.

“The whole Swedish football family is thinking of you and hoping you get well soon,” they said in an Instagram post.