John Tomic’s ATP ban will remain in place for at least a year after officials concluded their own investigation into the alleged assault of his son Bernard’s former training partner Thomas Drouet.

Tomic, who is also Bernard’s coach, had his tour credentials suspended indefinitely following the incident, which occurred during the Madrid Masters in May.

He denies assaulting Frenchman Drouet, saying he was acting in self defence, and the case will be heard in a Madrid court in October.

But ATP officials told AAP on Saturday Tomic would not be able to attend any ATP events in a coaching capacity until at least May next year.

“Our investigation into the incident has concluded and John Tomic’s credential privileges remain suspended at ATP events for a 12-month period from when the incident took place (May 4, 2013). The suspension will be reviewed at the end of the 12-month period,” the ATP said in a statement.

John Tomic has been able to attend his son’s last two events, at Queen’s and Eastbourne, as a ticket-holder, with ATP rules leaving it up to individual tournaments to determine whether he is allowed as a spectator.

He was barred from attending the French Open and will also be kept out of Wimbledon.

Bernard Tomic has stressed his father will always be his coach, but the ATP’s latest decision will continue to complicate matters.

Tomic recently revealed he’d made several changes to his coaching staff, drafting in Eugenio Forchione, Ivan Dimitrijevic and Harry Skinner as part of his support team.

The 20-year-old heads into Wimbledon having showed some encouraging form at Eastbourne, where he reached the quarter-finals.