Chelsea are confident they did not breach any rules by fielding Bertrand Traoré, the Burkina Faso international, as a 16-year-old in friendly fixtures amid fears that the Premier League champions may have left themselves open to a Fifa transfer ban.

Traoré was signed to professional terms by Chelsea on 1 January 2014, the day the transfer window opened after his 18th birthday, having been the subject of an “option agreement” before acquiring his registration and which, the club believes, allowed him to feature in what were effectively considered trial games. He had been at Auxerre’s youth academy.

The forward was photographed playing in an under-18s fixture against Arsenal at the Emirates stadium on 23 October 2011, when he was only 16, a game the clubs deemed to be “non-competitive”.

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Fifa rules prohibit the international transfer of a minor – an under-18 – with Real Madrid and Atlético Madrid having been handed transfer embargoes for the next two windows for alleged breaches of those regulations. Both clubs plan to contest the sanctions. Barcelona were banned from conducted transfer business for infringing the same rules in 2014 and have been permitted to register new players again only this month.

“Bertrand Traoré was registered by Chelsea in January 2014 in compliance with FA and Premier League Rules,” said a Chelsea spokesman. “Prior to that date, he was party to an option agreement which enabled the club to acquire his registration in January 2014. The option agreement was registered with, and approved by, both the FA and the Premier League.”

Fifa has not confirmed whether Chelsea are under investigation over Traoré. “We are not in a position to comment on any investigations that are ongoing so as not to compromise the process, nor do we provide any comments as to whether or not any investigations are under way,” a spokesperson told PA Sport. The Premier League is satisfied all rules were followed when the player signed professional terms in 2014.

International transfers are permitted for players under the age of 18 only if the player in question meets one of three qualifying criteria: if the player’s parents move to a new country for non-football reasons; if they are from another nation within the European Union or European Economic Area and aged between 16 and 18; or if they live within 100km of the club. It is unclear as to whether Traoré, who was born in Bobo-Dioulasso and shone as a 14-year-old at the 2009 Fifa U17s World Cup, met the first of those criteria, but the Burkina Faso sports minister Jean-Pierre Palm announced in August 2010 that the player would sign for Chelsea.

He went on to attend the fee-paying Whitgift School in Croydon between 2011 and 2013 where he was overseen by the former Chelsea defender Colin Pates in his capacity as head of football. José Mourinho took him as a triallist on the Londoners’ pre-season tour of Malaysia, Thailand and Indonesia in the summer of 2013, and he scored against a Malaysia XI in Kuala Lumpur.

“Now we want to keep him,” said Mourinho at the time. “We have to wait until he becomes 18 to try to get a permit for him to stay in England. It’s the rules and we have to accept them. He plays for his national team. Sooner or later the committee has to give him a permit to play in England.”

Traoré, now 20, has since spent time on loan at Vitesse Arnhem, and could seal another temporary switch before next week’s transfer deadline. Back in 2010, Chelsea successfully appealed against a transfer embargo at the Court of Arbitration for Sport which had stemmed from the signing of Gaël Kakuta, now at Sevilla, from Lens.