MP Jami-Lee Ross has been taken into mental health care.
Newstalk ZB understands he was taken in by police.
He was taken to a facility in Auckland.
A National Party spokesman said: "Over the past several weeks the National Party has taken seriously the mental health concerns raised by Mr Ross and the medical professionals he has been involved with. That has included seeking advice from medical professionals and involving Police wherever necessary to ensure support is made available to Mr Ross. It would not be appropriate to comment further."
Ross took leave from Parliament at the beginning of the month. He told reporters this week that it was because he was "devastated" at being accused of harassment and denied natural justice.
When he talked to media on Tuesday and Wednesday, he said that his doctor had cleared him and he was feeling healthy. He rejected comments from National deputy leader Paula Bennett that he was suffering from mental health issues, saying that his doctor had called Bennett to tell her that he was healthy.
Those comments were made before six women spoke publicly about what they called bullying and intimidating behaviour from Ross. Ross disagreed with the way the women portrayed him in media reports, but admitted to extra-marital affairs and said he had apologised to his wife Lucy Schwaner.
Paula Bennett has repeatedly expressed concern for Ross' health.
It is unclear if Ross was admitted under the Mental Health (Compulsory Assessment and Treatment) Act, which means that someone can be admitted to a safe place and given treatment against their will if their safety is considered at risk.
Ross' leave from Parliament at the start of the month followed a text message concerned about the mental health of the person who leaked details of National leader Simon Bridges' expenses. It led to speculation that Ross was the leaker, which he denies, even though an inquiry found that he was likely the leaker.
Act leader David Seymour has responded to the news on Twitter:
Former National MP: Jobs should go over Jami-Lee Ross
Former National MP Tau Henare is calling for National Party president Peter Goodfellow'sjob to go for allegedly trying to cover-up Jami-Lee Ross' conduct with women.
But one of the women who has accused Ross of bullying behaviour, Katrina Bungard, is defending the party, saying she always felt supported by the party leadership.
Several women have spoken out against Ross, including one who described working for Ross as "death by a thousand cuts".
Four other women had earlier spoken to Newsroom about what they called manipulative and intimidating behaviour from Ross, with one saying he would go into "incoherent rages". Two of them said they had sexual relationships with Ross.
Ross has responded to the four women by disagreeing with how he has been portrayed, but apologising for any "hurt" he had caused them and admitting to extra-marital affairs - one with a married MP.
He said he apologised to Bungard, who is the Howick Local Board deputy chairwoman, during mediation that was facilitated by National Party president Peter Goodfellow.
But he accused the party of burying the matter by getting Ross and Bungard to sign non-disclosure agreements.
This morning Tau Henare, a National MP from 2005 to 2014, said via Twitter that jobs should go.
"More Heads should roll in @NZNationalParty over the #JLR meltdown. You cannot protect the abuser and hush the victim because it will hurt your brand. You damage your brand by covering s*** up."
In another tweet, Henare said that the party hierarchy had handled Ross poorly by "sweeping shit under the mat. So much so that the story broke it victimised the women in question again. #HeadsWillRoll".
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call 111.
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.
There are lots of places to get support. For others, click here.