Onana tested positive for furosemide, a banned diuretic, in a urine sample given last October, the Dutch club said in a statement.
Friday’s decision to not award the Dutch league title to Ajax Amsterdam was understandable, said the club’s general manager Edwin van der Sar as the season in the Netherlands was formally brought to a premature close by the COVID-19 pandemic.
Ajax are in talks with Nouri's family about a future solution for the player, who has been moved to a specially adapted room at his home after years in hospital
Former Manchester United goalkeeper Edwin van der Sar reappointed as Ajax chief executive until 2023
49-year-old Van der Sar has been in charge at the Johan Cruyff Arena since 2016, helping the club win last season's Dutch league title and reach the Champions League semi-finals
UEFA Champions League: European giants set to get the ball rolling again amidst talks of tournament revamp
While the battle for the Champions League of the future is fought behind the scenes, this week the continent's biggest clubs begin their latest quest for European glory with holders Liverpool dreaming of reaching another final in Istanbul.
Ajax CEO Edwin van der Sar defends controversial European Super League plan, claims stability of clubs depends on competition
Edwin van der Sar has defended controversial plans to reform European competitions by claiming the stability of clubs depends on them playing more European matches.
European clubs demanded that UEFA 'properly include' them in any plans to change the Champions League, which could ensure top teams play more regularly.
Premier League: Ole Gunnar Solskjaer confident David de Gea will sign new contract with Manchester United
Ole Gunnar Solskjaer is confident Manchester United will be able to retain the services of David de Gea, who he rates as the best goalkeeper in the world.
Champions League: Edwin van der Sar uses 'knowledge' of former Ajax teammates to nurture exciting talents
Van der Sar was at the table when Frenkie de Jong, Ajax's latest superstar of tomorrow, was granted a 75 million-euro ($66.3 million) move to Barcelona last month.
Dutch football giants Ajax announced a five-year partnership with Chinese Super League (CSL) side Guangzhou R&F on Monday that will attempt to build the best youth academy in China.
Twenty-two people were killed and 250 injured by a suicide bomber in Manchester in May before attacks in Barcelona earlier this month left 16 dead and over 150 injured.
Ajax's 20-year-old midfielder Abdelhak Nouri suffers permanent brain damage after collapsing in the training
Ajax midfielder Abdelhak Nouri has suffered "serious and permanent" brain damage after collapsing dashing earlier hopes the promising prospect would make a quick recovery.
World Cup qualifiers: Netherlands mark Dick Advocaat's return as manager with 5-0 thumping of Luxembourg
Advocaat, who had previously managed the Dutch national side from 1992-94 and from 2002-04, was brought on board after predecessor Danny Blind was sacked.