Justin Thomas has apologised for using an anti-gay insult at the Sentry Tournament of Champions yesterday.

Justin Thomas has been heavily criticised on social media after he was heard muttering a homophobic slur during the third round of the PGA Tour's event in Hawaii.

His mike clearly picked up the insult when he missed a 5-foot par putt on the fourth hole of Kapalua’s Plantation Course.

Speaking after his round, the former World Number One apologised and called his language 'inexcusable'.

"First off, I just apologize. I'm an adult. I'm a grown man; there's absolutely no reason for me to say anything like that. It's terrible. I'm extremely embarrassed. It's not who I am; it's not the kind of person that I am or anything that I do." he said.

"Unfortunately, I did it, and I have to own up to it, and I'm very apologetic."

He also he wasn't aware that the comment had been picked up on his mike and was being discussed on social media until after his round.

"It's bad. There's no other way to put it," he continued.

"I need to do better; I need to be better. It's definitely a learning experience. I just ... I deeply apologize to everybody and anybody who I offended, and I'll be better because of it."

The insult has understandably angered and offended many golf fans, with lots of people taking to Twitter to express their disgust and sadness.

Sky Sports reporter Jon Holmes commented that such discriminatory language is 'ingrained' in sporting culture and 'so damaging'.

Sky Sports commentator Sarah Stirk also commented: "He had no idea he’d even said it which means that sort of language is pretty commonplace for him. It's worrying and very telling."

However, others have dismissed the comment, saying that as it was aimed at an object (a golf ball), to be offended by it is being overly sensitive.

Here at Women & Golf we find his language totally unacceptable and the the PGA Tour has said in a statement that the organisation views it as such, too.

Justin is likely to be fined for his conduct, but as the PGA Tour doesn't generally disclose its punishments, it's unlikely that his penalty will be revealed.