A Champions League soccer match between Paris St.-Germain and Istanbul Basaksehir was suspended on Tuesday after both teams accused a match official of directing a racial slur at a Black assistant coach.

The game in Paris — a crucial fixture in European soccer’s showpiece competition — was interrupted after just 14 minutes when Sebastian Coltescu, the Romanian fourth official, summoned the referee, Ovidiu Hategan, to the sideline. It was not immediately clear what had prompted the request.

As Hategan approached the team benches, Coltescu appeared to ask that Pierre Webó, the former Cameroon international now working as the Turkish team’s assistant manager, be ejected from the match.

Reports in Romania, and audio of the incident, suggested Coltescu communicated to Hategan that a member of the Basaksehir coaching staff — Webó — should be dismissed, and pointed him out as “that Black one.”

As Hategan prepared to produce a red card from his pocket, Webó approached the referee and accused Coltescu of using a racial epithet in singling him out.

“Why did he say negro?” Webó shouted repeatedly in the direction of Coltescu as he was sent away from the field. “Why did you say negro?”

Basaksehir’s players immediately protested to Hategan. Demba Ba, the team’s veteran Senegalese striker, then approached Coltescu and asked him, “Why when you mention a Black guy, you have to say, ‘This Black guy’?”

“You wouldn’t say ‘these white guys,’” Ba said, pointing his finger. “You’d say ‘these guys.’”

Coltescu, whose role as the fourth official involves policing the coaching areas and benches and handling player substitutions, appeared to defend himself by saying it was an issue of language, not intent.

After several minutes of discussion, Basaksehir’s players decided to leave the field, and they were swiftly followed by their counterparts from P.S.G. As he left the field, Hategan could be overheard on the television broadcast’s microphones insisting that the protocol for dealing with the issue — and whether the game would be restarted — was “not up to me.”

UEFA, European soccer’s governing body and the competition’s organizer, initially planned for the game to resume at 10 p.m. local time, after a delay of 45 minutes, with Coltescu replaced by the official serving as the on-site video assistant referee.

P.S.G.’s players were reported to be willing to continue playing — even returning to the tunnel to make their way to the field — but Basaksehir confirmed on Twitter that its players had refused to do so “because of the racism of the fourth official, Sebastian Coltescu, against our assistant coach Pierre Webó.”

P.S.G. also publicly confirmed that “racist remarks from the fourth official” had prompted the stoppage in play.

Two hours after the players left the field, UEFA said in a statement that the teams had agreed to play the final 76 minutes of the match on Wednesday after it had agreed to the unusual conditions of replacing the entire crew of match officials. It also said it would review the incident that led the game to be halted.

“A thorough investigation on the incident that took place will be opened immediately,” UEFA said in a statement.

P.S.G. will go into it knowing that its place in the tournament’s knockout rounds is secure, after Manchester United’s defeat to RB Leipzig on Tuesday night sealed the elimination of the Premier League club. Basaksehir had already been eliminated from the competition.