Published Friday, 23 May 2014
Party Leader Basil McCrea with deputy John McCallister and Tina McKenzie in 2013 (© Pacemaker)
The Lagan Valley MLA confirmed on Friday morning that he has emailed his colleagues to acknowledge that claims have been levelled against him.
Mr McCrea told the BBC he has done nothing wrong and said the allegations were only brought to his attention on Thursday.
"There obviously are social media rumours and such like, there is a specific allegation coming forward now, and now there is such a thing, then I can go and respond to it," the NI21 leader said.
"In these issues it's important you respond in the appropriate way and I will be looking to see how we can do that."
It comes after a disagreement emerged between Basil McCrea and party deputy leader John McCallister this week when NI21 changed its designation from 'unionist' to 'other'.
Mr McCallister has described the change as "crazy" and said that it showed how "dysfunctional" the party had become.
No matter what happens, Basil McCrea and John McCallister are damaged politically
UTV’s Political Editor Ken Reid
The South Down MLA has claimed it was orchestrated to force him out because he had raised allegations about Mr McCrea's behaviour.
Mr McCallister said it was an attempt to thwart an external report into his conduct, adding: "The report comes to me, so if I was not in position, therefore, the process could be easily stopped."
The developments come after NI21's European candidate Tina McKenzie dramatically resigned from the party executive on Thursday night a short time after polls closed in Northern Ireland.
Speaking to UTV at the count in Belfast on Friday, she said: "I'm absolutely devastated.
"I've worked for the last year on this campaign and done everything I could do personally to bring the party to where we brought it to as a team.
"You've heard from Basil and you've heard from John and I categorically, alongside the Executive, have said that we will not be discussing the details with any media until we discuss it with those 46 candidates. The candidates at this stage need be given the absolute facts."
She failed to be elected in Belfast's Balmoral District Electoral Area, where she competed in the local Government poll.
Earlier Ms McKenzie tweeted: "So sad that freshpolitics has been let down by old politicians. I have resigned from the Executive but still fully support NI21.
"If elected I will stand but will not work for people who play dirty tricks and dirty politics."
She later deactivated her Twitter account.
UTV's Political Editor Ken Reid said NI21 may now be finished. He continued: "Almost by the hour the situation for the party seems to be worsening.
"Basil McCrea this morning has confirmed what the allegations against him actually are - and he vehemently denies them - but they are in a pretty difficult, indeed hopeless, situation.
"It is unusual in Northern Ireland to have a new party, two very high-profile media performers, then the whole thing is fought out in the media.
"The party as such, in my opinion, is finished. I just don't see a way back."
© UTV News