Sweden midfielder Kristoffer Olsson is on a ventilator in hospital after collapsing at home due to a brain condition, his club Midtjylland have announced.

The 28-year-old, who had a spell at Arsenal as a teenager, has not appeared for the Danish club since December and there had been mounting speculation over his absence.

Midtjylland said in a statement on their official website: “In view of the increasing rumours and speculation that are circulating about the reason for Kristoffer Olsson’s absence in the recent period, we are forced to make this announcement to the public.

“The 28-year-old Swedish international lost consciousness in his home on Tuesday 20 February and was transferred to Aarhus University Hospital, where he has been admitted and on a ventilator.

“Kristoffer Olsson is affected by an apparently acute disease related to the brain, which is not caused by self-harm of any kind, nor is the cause due to external factors.

“A team of Denmark’s leading medical experts is currently working hard to make a diagnosis and initiate the right treatment.”

Midtjylland called for “respect and understanding” and added: “Everyone at FC Midtjylland is of course deeply affected by Kristoffer’s sudden illness and our thoughts and full support go to Kristoffer and his family.”

Arsenal wished Olsson, who has won 47 caps for his country, a “full and speedy recovery” on social media.

Olsson joined the Gunners from Swedish side Norrkoping aged 16 and made one senior appearance as a substitute in a League Cup game against West Brom.

He is currently in his second permanent spell with Midtjylland and has also had stints at AIK, Krasnodar and Anderlecht.