Ajax midfielder Abdelhak Nouri suffered “serious and permanent brain damage” after collapsing in a friendly match on Saturday.
The 20-year-old had “cardiac arrhythmias” – heart rhythm problems – during the game against Werder Bremen.
The club statement said the chances of recovery from the damage are nil.
It added: “The diagnosis was made that a lot of [his] brain is not functioning. All this probably occurred due to a lack of oxygen supply.”
On Monday, the club had said tests showed his “heart is functioning normally” and brain scans did not detect “any anomalies” – but new tests revealed the extent of the damage.
Nouri played 15 league and cup games for Ajax in 2016-17, scoring one goal in a Dutch Cup tie.