The National Party will pull its support for a government bill to allow those with terminal conditions to access medicinal marijuana and instead put up its own "more comprehensive" bill on the issue.

The health select committee is finalising its report on the Government bill tomorrow and is likely to be tabled in Parliament. It is still likely to be passed with support from Labour, the Greens and New Zealand First, despite National dropping its support.

National had supported it at first reading but said its ongoing support was dependent on what changes were made in select committee.

National leader Simon Bridges said the party had now decided to pull its support for that bill and develop its own measure, which he said would set out a more comprehensive and well researched regime for the use of medicinal cannabis.

"National supports greater access to high quality medicinal cannabis products to ease people's suffering but we must have the right regulatory and legislative controls in place.

"Among other things, our bill is going to make clear who can buy medicinal cannabis, who can sell it, and exactly how that will work."

That will be put into the members' bill ballot in the name of Shane Reti. However, there is no guarantee it will ever be considered by Parliament because member's bills are chosen by the luck of the draw.

It will include a regulatory and legislative regime to set out who is eligible and who can dispense marijuana for medicinal purposes.

The Government's bill would allow only people with a terminal condition to access medicinal marijuana and was criticised by many submitters for being too narrow.

NZ First had supported the Government bill but wanted a referendum on the issue as well. A referendum will be held before or at the 2020 election as part of Labour's confidence and supply agreement with the Greens - but that vote will be about the personal use of cannabis.

Green MP Chloe Swarbrick put up a more liberal bill under which those in pain would also have been able to use medicinal marijuana and allowed people to grow it, which was defeated at first reading in January.

The latest moves come as the NZ Drug Foundation's annual poll on the issue shows support to decriminalise or legalise cannabis for the use of pain relief has increased from 78 per cent last year to 87 per cent this year in what has become an annual survey.

Using cannabis for pain relief for terminal conditions is even higher, at 89 per cent.

Support for personal possession is up to 67 per cent from 65 per cent and support for personal growing of cannabis is up to 61 per cent from 55 per cent.

There was much less support for selling cannabis as a retail product from a store, only 38 per cent supported that - up from 34 per cent last year.