Chelsea have been asked to confirm the number of games Bertrand Traore played for them as FIFA's investigation into the player's move to the club intensified on Wednesday night.

Although the initial inquiry centred on his surprise appearance for Chelsea in an Under 18 friendly against Arsenal at the Emirates in 2011, it is now believed he may have played in a number of behind-closed-doors games.

Chelsea are under pressure to confirm whether the Burkina Faso international played for the club on a trial basis.

Chelsea have been ordered to come clean over the number of games Bertrand Traore played for them

The talented midfielder has broken into the Chelsea squad and has made his Premier League debut

TRAORE CHELSEA CAREER STATS Chelsea - two appearances (Maccabi Tel Aviv and Bournemouth) Advertisement

They have been reported to FIFA because Traore's name appeared on the Arsenal website following the fixture, in which he should not have played.

Traore, aged 16 when that game took place, had not been registered to play for Chelsea.

International regulations prevent the transfer of minors — including any player under 18 — unless they meet strict criteria.

It is claimed Traore did not satisfy the qualifying parameters. It is understood that the club believed they could play Traore in non-competitive games. Chelsea declined to comment.

The report on Arsenal's official website mentions Traore brushing the top of the crossbar in the friendly fixture

The attack-minded player was a trialist on Chelsea's pre-season tour and he caught Jose Mourinho's eye

Traore emerged at the 2009 FIFA under-17 World Cup. At 14 he was the youngest player in the tournament.

He agreed a move to Chelsea in August 2010, according to Burkina Faso sports minister Jean-Pierre Palm, one month prior to his 15th birthday.

FIFA regulations say players aged over 16 can move within the EU, but broader international transfers must be over 18. Rule 19.1 on the protection of minors states: 'International transfers of players are only permitted if the player is over the age of 18.'

Barcelona were handed a transfer embargo after being found guilty of breaching the regulation. Real Madrid and Atletico Madrid are contesting similar sanctions.

Traore spent 18 months on loan at Dutch side Vitesse Arnhem, who act as a feeder club to Chelsea

Traore travelled on Chelsea's pre-season tour to Bangkok, Kuala Lumpur and Jakarta in July 2013

The 20-year-old is a full international with Burkina Faso and has made 24 appearances for his country