Crusaders players, including All Blacks winger George Bridge, were accused of directing homophobic slurs and gestures at patrons at a fast food restaurant over the weekend.
In a separate incident, the team's flyhalf Richie Mo'unga, also an All Black, was alleged to have spat beer at people at a night-spot earlier in the week.
The three Crusaders players embroiled in the restaurant incident "strongly refuted" allegations of homophobia, the team said on Monday, while coach Scott Robertson played it down as a misunderstanding over a 'selfie'.
But with witnesses coming forward to criticise the players on local radio, New Zealand Rugby said it had launched a probe.
"The allegations that have been made about players, in two different incidences, are very serious," New Zealand Rugby's Chief Rugby Officer Nigel Cass said in a statement on Tuesday.
"These allegations are about abuse, inappropriate and offensive behaviour, and we do not tolerate this.
"At the same time, the players are refuting the details of the claims made. Because the nature of these allegations is serious, it is important that we carefully look at these claims without prejudice or assumptions."
Crusaders CEO Colin Mansbridge said on Tuesday the players involved were "distraught about the accusations" and continued to refute them.
"Clearly the right thing to do is to formalise the investigation into these matters, which would allow both sides to be heard."
'SELFIE GONE WRONG'
Crusaders coach Robertson defended his players late on Monday after arriving back from South Africa.
He said Bridge had wanted a photo with one of the patrons at the restaurant.
"There was no interaction with anyone else," Robertson told local media.
"That's where the misinterpretation came. A selfie gone wrong, really."
On Monday, a local Twitter user posted an account of the incident that accused the players of being "physically intimidating" and mocking his friends with high-pitched voices and homophobic gestures.
"Where it is now is amazing to us. As a team and as a culture, our values have been strong," said Robertson.
"We understand what's happened across the ditch (in Australia) and it's in the forefront of our mind. We've talked about it as a group."
On Friday, Australia fullback Israel Folau had his four-year contract terminated for posting on social media that hell awaited "drunks, homosexuals, adulterers" and others.
A Cape Town man who identified himself as a friend of the accusers told New Zealand media that he had asked one of the players why he was filming his friend with his mobile phone.
"He then said, 'Well, we look funny'," the man, who only gave his first name as Jeremy, told Radio New Zealand.
"I am speaking for the queer community of South Africa and Cape Town in voicing that we are tired of these experiences."
Following reports of the restaurant incident, a woman came forward to accuse Mo'unga of spitting beer on her and her friends.
She told Radio New Zealand that Mo'unga had apologised to her the next day when she contacted him via Instagram.
Radio New Zealand posted a screenshot of Mo'unga's apology in which he admitted to being drunk.
"Obviously was intoxicated and should've gone home long before that stage, I'm sorry to you and your friends and want to assure you I don't condone that behaviour and am sorry about that," the post said.
(Reporting by Ian Ransom in Melbourne; Editing by Greg Stutchbury)
