Mia Culpa. We were responsible for Sanchez at the time, said Wenger. Photo: Peter Powell/BackpagePix

LONDON – Arsene Wenger insisted Arsenal were at fault if Alexis Sanchez had missed a routine drugs test on the same day as he was completing his transfer to Manchester United.

Reports in the British media late Thursday suggested the Chile forward had contravened the Football Association's 'whereabouts' rule by missing a doping test scheduled for Monday -- the same day as a move to Premier League rivals United was being completed.

The 'whereabouts rule' in the Premier League gives players a responsibility to update their individual details.

The system aims at making it easier for anti-doping authorities to conduct tests.

Sanchez's 'whereabouts' changed on Monday when he moved to Manchester United, although it appears the Chile forward was still technically a registered player with London giants Arsenal when the possible infraction of ant-doping rules took place.

“It is just a bad day for him to be tested,” Arsenal manager Wenger told reporters on Friday. “Honestly, on the administration side it would still be our responsibility because he had not moved.

“The intention of Alexis was not to hide -- and we have nothing to hide,” the veteran French manager added. “On Monday there was a lot going on, it is a special day for Alexis Sanchez - you have to do paperwork and travel.”

Premier League leaders Manchester City were interested in signing Sanchez before hearing of the Gunners' reported £35 million ($50 million, 40 million euros) price tag and the player's wage demands.

That paved the way for United to clinch a straight swap deal that saw Henrikh Mkhitaryan join Arsenal.

Sanchez could make his United debut later Friday after being included in the squad selected by Jose Mourinho for the FA Cup fourth-round tie away to fourth-tier club Yeovil Town.