Mike Phillips' indefinite suspension from the Wales squad has been lifted after he apologised to Wales Rugby Union (WRU) bosses.
The British and Irish Lions scrum-half, who earlier this month completed a move from Ospreys to French club Bayonne, was banned "with immediate effect" on June 17 following a late-night incident in Cardiff city centre.
Phillips, who was not arrested and is not facing any criminal action in relation to the incident, met with head coach Warren Gatland, assistant coach Rob Howley, and national squad manager Alan Phillips on Monday.
The WRU later released a statement confirming that the 28-year-old would be allowed to return to the squad from Tuesday and take part in World Cup training.
"Mike Phillips met with the senior Wales squad management today, following his suspension on Friday, June 17," the statement read.
"The player was informed his conduct in Cardiff city centre, earlier that week, had not adhered to the standards expected of a member of the Wales senior squad.
"Phillips accepted the view of the senior management team in full and gave an assurance that he understands the action taken to punish his behaviour and is taking active steps to ensure there is no repeat.
"The player addressed the Wales extended Rugby World Cup training squad players, explained his conduct and outlined his plans to ensure there is no repeat of the incident and apologised.
"Following the meetings and taking into account the duration of the 10-day suspension, Phillips will now be allowed to return to the squad and take part in pre-Rugby World Cup training from tomorrow, Tuesday, June 28.
"The senior squad management panel he met at their headquarters in the WRU national centre of excellence, consisted of head coach Warren Gatland, assistant coach Rob Howley, and national squad manager Alan Phillips."
Gatland said: "Mike clearly breached the disciplinary code of conduct we have in place and was dealt with decisively and properly.
"We have taken into account all the relevant issues and Mike's apology in taking the decision to reinstate him in the extended RWC squad.
"An important factor in allowing Mike back into the squad was his decision to actively seek help to resolve his behavioural issues."
Phillips admitted said he was ashamed by his behaviour and should not allow his aggressive style on the pitch to manifest itself off it.
"This is the most embarrassing thing that has happened to me in my career," he said. "I am ashamed to have let myself get into this kind of situation and I am determined to put things right.
"As a player I'm really passionate and never back down. I know I can't allow that part of my character to come to the surface off the rugby pitch.
"I have realised I have an issue with the way in which I deal with, and have dealt with, the pressures of my current environment and have sought, and will continue to seek, help and advice in relation to that issue.
"I have formally and sincerely apologised to my team-mates and the coaching staff in the Welsh squad and would like to take this opportunity to do exactly the same to the Welsh rugby public and anyone else who has been offended by this or other episode.