Two more women have come forward saying they were sent indecent material by former National MP Andrew Falloon, party leader Judith Collins says.
Collins said police have told her they would "most likely" be reopening their investigation.
"I now need to seek permission from those women who have contacted me to be able to pass on that information to police."
Yesterday it was revealed the Rangitata MP apparently sent an indecent image - not of himself - to a 19-year-old woman and had announced he would retire at the election.
This morning he wrote to Collins and Parliament's Speaker Trevor Mallard to resign with immediate effect, after reports of the new claims emerged.
Collins said she spoke to the 19-year-old on the phone this morning, and protecting her confidentiality was of utmost importance.
Shortly before Falloon's resignation, Collins told Morning Report she had been told of further allegations and could no longer trust the MPs story.
"I think he should resign from Parliament today, now that there are further statements and I can no longer trust his story. I believe that that would be the best thing for him ultimately. He is clearly now with his family and receiving professional assistance. It is I believe better for him, better for the young woman who is my first priority, and for Parliament, that he resigns.
"It was clear to me yesterday that he was admitting what was being alleged, what had been alleged by the young woman, and that I've now been advised by media that Andrew Falloon has now changed his story."
Collins said she had not seen the image in question. But she said it was of a pornographic nature and not of a male.
"My first priority yesterday was the young woman who is now dealing with the terrible trauma and I've reached out to her and made it very clear that if there's any assistance I can give I will do so."
Police investigated Falloon after receiving the report, but determined it did not meet the threshold for prosecution.
"I have no questions in my mind, no doubt that he did send that message," Collins said. "Any suggestion that he didn't is simply wrong."
He only knew the young woman in a professional sense, Collins said.
"It was clear to me yesterday that he was admitting what had been alleged.
"I am very concerned because I have today - it was very early this morning - received advice from media of other instances of this with at least another person.
"That indicates that it is unlikely to be a solitary incident.
"It may well be a pattern of behaviour - but the only thing I have to go on is the information from the media and I have not seen the evidence myself.
"But I do believe that with my priority being the young woman, and any other women who have received this sort of of pornographic imagery, that Andrew Falloon should today resign from Parliament.
"Obviously he has, from what he has said to me, significant mental health issues, however I am very very aware of the young woman involved, and any other women involved if this is a pattern of behaviour."
Collins said: "If they have any [information] and they wish to provide it to me it would be treated with the utmost confidence... I would treat this extremely seriously".
The National Party was notified on late Friday afternoon of an alcohol-related incident involving Falloon in which he behaved in a way "unbecoming of an MP".
The initial correspondence had gone to the Prime Minister's office on Wednesday. Jacinda Ardern said her office had handled the matter properly.
"I had a quick discussion with my office about the best way to handle it. The most important thing for us was that nothing happened without the permission of the person who had written. We sought permission for it to be shared with the [National Party] leader."
Ardern said once that permission was granted the information was given to the National Party leader and that was the end of her office's involvement.
"We shared it with the leader of the Opposition and that was the only place it was appropriate for it to be shared."