The New South Wales Government is running months behind schedule on its medicinal cannabis trials, with the trial for terminally ill cancer patients now unlikely to begin this year.

Key points: Three trials were scheduled to be launched in 2016 but only one has begun so far

Three trials were scheduled to be launched in 2016 but only one has begun so far The trial for terminally ill cancer patients, initially meant to begin in early 2016, missed its July launch date

The trial for terminally ill cancer patients, initially meant to begin in early 2016, missed its July launch date The ABC understands the Government had trouble sourcing a suitable placebo for the trial

The delay has infuriated advocates like Garry Clarke, whose wife Roxanne died in June from melanoma.

"I was promised — and Rox was promised — that the trials would start in early July," Mr Clarke said.

Premier Mike Baird announced in December 2014 that three trials would be launched in 2016 — one for paediatric epilepsy, one for adults with terminal cancer and another for chemotherapy patients suffering nausea and vomiting.

As 2016 draws to a close, the only one to have begun is the trial for children with epilepsy.

The trial for terminally ill cancer patients, initially meant to begin in early 2016 according to the Government's own fact sheet, has missed its latest target of a July launch.

The first phase of the trial is supposed to involve about 30 patients to determine the optimum dosage, the delivery method and possible side effects of medicinal cannabis.

The second phase would then test the medicinal cannabis against a placebo in a state-wide trial involving about 300 patients to see whether those who used a cannabis product had better, worse or similar outcomes.

The ABC understands the Government has had trouble sourcing a suitable placebo to test against the medicinal cannabis in order to conduct the second phase of the research, but has also chosen not to begin the first phase until the issue is resolved.

A source has told the ABC the first phase is now unlikely to begin this year and would take about three months to complete.

Do you know more about this story? Email wordsworth.matt@abc.net.au

'Get off your arse, address the issues'

Labor's shadow minister for medical research, Tania Mihailuk, said the Government had boasted of leading the way on medical research and described the delay as "appalling".

"Why build up such hope and expectations if you are not prepared to negotiate contracts and conduct these trials swiftly?" Ms Mihailuk said.

"For there now to be such a significant delay will distress unnecessarily many patients desperate to trial the treatment."

Mr Clarke holds Mr Baird and the Minister for Medical Research, Pru Goward, responsible.

"My attitude is get off your arse, address the issues and realise we're wasting time," Mr Clarke said.

"Stop dicking around. Stop telling us lies about where we are with medicinal cannabis. Get this trial back on track."

A NSW Government spokeswoman did not give a new estimate on when the trial would begin but said the Government wanted it to be "as soon as possible".

"This is the first time in Australia that a botanical cannabis product has been used in a trial," she said.

"Obtaining approvals for the placebo from the Dutch authorities has taken longer than expected. Within weeks of placebo arriving in the country, the researchers will be in a position to commence patient enrolment."

The spokeswoman said an announcement about patient enrolment for the chemotherapy-induced nausea and vomiting trial would be made "shortly".