The president of the PGA of America has apologised for the US fans' abuse of Rory McIlroy at the Ryder Cup last weekend, saying some spectators had "clearly crossed the line".
Don Rea had initially played down the comments from the crowd at Bethpage Black, which were particularly aimed at Europe's star player McIlroy.
He was criticised for doing so by Team Europe's Matt Fitzpatrick, and has now apologised.
"Let me begin with what we must own. While the competition was spirited - especially with the US team's rally on Sunday afternoon - some fan behavior clearly crossed the line," he wrote in a letter to golf professionals.
"It was disrespectful, inappropriate, and not representative of who we are as the PGA of America or as PGA of America golf professionals," Rea wrote.
"We condemn that behaviour unequivocally."
Europe held off a stirring fightback from the United States to win 15-13 and retain the Ryder Cup.
The vitriolic comments rang out from the crowd during Saturday's day of play and video showed a beer being slapped out of a fan's hand towards McIlroy's wife.
There was further controversy when a comedian hired to lead cheers incited the crowd to verbally abuse McIlroy.
US veteran Tom Watson condemned the unruly American fans, saying he was "ashamed" of their behaviour.
The Europe team responded to their win by recording a social media video in which they chanted "Are you watching, Donald Trump?" The US president had attended the first day's play.