A bill that would ban conversion therapy has passed its second reading in Parliament.

Conversion therapy involves attempts to change a person's sexual orientation or gender.

All parties except National block voted in favour of the bill.

National's leader Christopher Luxon announced in the lead up to the bill that his MPs would be able to vote with their conscience.

In total, 26 of National's MPs voted for the bill and seven voted against it.

The select committee heard oral submissions from 837 submitters in total, made up of 716 individuals and 121 organisations.

Among the concerns raised were that parents could be criminalised.

However, the select committee found that "conversations between parents and children would not be criminalised under the offence in clause 8".

"We believe that the standard for a behaviour to be considered a conversion practice in the bill is appropriately high," it says.

The MP in charge of the bill, Labour's Kris Faafoi says the bill received the largest ever number of submissions in Parliament's history.

He thanks the Justice Select Committee for listening to harrowing submissions of people who had undergone conversion therapy and from those stuck in a time where the diversity of gender and sexual orientation was not accepted.

-RNZ.