Arsenal have banned the mother of young player Ainsley Maitland-Niles after she was involved in a training-ground dispute and threatened to withdraw the winger from an under-21 match.
Police were called and arrested Jule Niles after she confronted executive Dick Law and her son's agent.
No charges ensued but she has been subsequently issued with a warning.
Maitland-Niles, 17, has been at the club since he was nine and made his senior debut this season.
The teenager, who still lives at home, is highly rated by Arsenal officials and BBC Sport understands their biggest concern surrounds his focus following incidents of this nature.
Maitland-Niles made his first-team debut in a Champions League victory over Galatasaray in December, becoming the club's second-youngest player to feature in the competition.
He has also played as a substitute in Premier League and FA Cup games this season.
Niles arranged to meet Law, Arsenal's main contract and transfer negotiator, and her son's agent last month to ask about her son's progress at the club. It is understood a confrontation ensued, with Law and the agent suffering minor injuries.
Niles was banned from the training ground but managed to attend last week's under-21 game against Aston Villa, at which she is alleged to have shouted at coaching staff and threatened to withdraw her son.
Police were called again and, although no arrest was made, Niles was issued with a warning.
A police spokesperson said: "Police were called at 4.11pm on March 20 to the location to reports two people had allegedly been assaulted by a woman. They suffered superficial injuries.
"Officers attended and a 36-year-old woman from Watford was arrested on suspicion of assault. She has since been released with no further action to be taken against her.
"Police were called to the location on 24 April at 2.40pm to reports a woman was refusing to leave the premises.
"Officers attended and the woman was issued with a warning."
Arsenal declined to comment on the story.