Liberal MP Ian Blayney has broken party ranks to publicly express his support for the use of medicinal marijuana in Western Australia.

In direct contrast to his party's views, Mr Blayney said the Government needs to seriously consider making the drug available to terminally ill people to help with pain relief.

The Geraldton MP has written a letter to the Minister for Health, Dr Kim Hames, requesting a clinical trial for medicinal marijuana be undertaken.

Mr Blayney said he formed his opinion after discussing the topic with residents of his electorate in the Mid West.

"I'm just saying for people, especially who are in a lot of pain at the end of their life, if this could help them, I'd like to see them have access to it in some way," he said.

"It's very much an opinion I've come to from dealing with my constituents.

"It's not an issue that's ever been brought up as far as I know in the Liberal Party groups that I work in.

"The cases I've dealt with since I've been a member are ones where people have got cancer or, in one case, the results of treatment for cancer that have left them with a huge amount of pain.

"The other cases are those ones where people literally only have weeks to go and they can be in quite a lot of pain.

"I would like to see it properly trialled to figure out to see if it can help people in that situation."

Mr Blayney said there needed to be an easier way for terminally ill people to access the drug for trials.

"You would have to go through this whole process to set up the trial, you've got to have doctors involved, it's a very complicated process," he said.

"Especially when people are at that stage of their life and they're suffering a hell of a lot of pain, to tell them they've got to go through this rigmarole to have this trial just to see if this stuff helps you, I just think that's probably too tight.

"There should perhaps be another mechanism where people in that situation can get this stuff and just try it and see if it helps them, in particular in an ointment form, that seems to be the way."

Legalising cannabis sends wrong message: Liberals

A spokeswoman for Dr Hames said the Liberal Party's position was that legalising cannabis would send the wrong message to the community and undermine efforts to reduce illicit drug use and the harm it causes, particularly among young people.

The Liberals said the Therapeutic Goods Administration had not approved cannabis for therapeutic use in Australia and, at this point in time, the use of cannabis for medicinal purposes was at best experimental.

The spokeswoman said international experts, including the World Health Organisation, continued to recommend the need for more research and controlled clinical trials.

WA Labor leader Mark McGowan last month told his party's state conference that cannabis should be legalised for medicinal purposes.

Mr McGowan said people with terminal or chronic illnesses should be able to access medicinal cannabis in the form of tablets or sprays to ease their pain.

He said he did not support the softening of laws surrounding recreational drug use but would like to give doctors the power to prescribe cannabis when other medications had failed.

"Why should anyone have to suffer in agony if there's another way to relieve their pain?" he said.

"Why should they be treated as criminals?"

Blayney won't reveal if he plans to cross floor

Mr Blayney would not be drawn on disclosing if he would cross the floor and vote with Labor if a bill regarding the legalisation of medical marijuana was ever tabled in Parliament.

"I'd have to do some pretty deep hard thinking about that and as usual I'd be listening to my constituents," he said.

"I'm a bit amused by this because a while ago Mark McGowan told me that I was the most conservative member in the house, so it's quite funny that suddenly I seem to be his best friend on the issue.

"I think it's a good thing to get the issue out there in public and kick it around it a bit and see what comes out and what people think.

"I'd be interested to see if I get a bit of feedback back into my office.

"It may help some people, but it might do absolutely nothing for other people, but for those people that it does help and for where they are at that point in their life, I think it should be there for them to try."