A suspected heroin overdose has taken place in Melbourne just metres from where the Victorian Premier was announcing a safe injecting room trial.

Ambulance Victoria confirmed it was called to a suspected overdose in heroin hotspot North Richmond, where Daniel Andrews was in the middle of a press conference announcing the trial.

Legislation to open the room at the North Richmond Community Health Service will be introduced into parliament on Tuesday.

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An angry local points out the drama to Victorian premier Daniel Andrews. Photo: AAP

Former premier Jeff Kennett will oversee an expert panel that will monitor the program once it's up and running.

There were 34 heroin-related deaths in North Richmond last year and 34 already this year.

"This is a change in policy, there's no doubt about that, but it's a change that's needed," Mr Andrews told reporters.

"We have the highest heroin death toll since 2000."

The facility will only be open to people 18 years and older, illicit drugs won't be provided or dealt at the facility, there will be extra CCTV cameras and Victoria Police and the Department of Health and Human Services will be involved.

The Victorian Labor government had previously opposed a heroin injecting trial, but the mounting deaths and need to win a by-election against the Greens in the inner city seat of Northcote helped reverse that decision.

Reason Party MP Fiona Patten, who led the push for a safe injecting room, hailed the government's about-face as a win for evidence-based policy.

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The suspected overdose victim is helped to an ambulance. Photo: AAP

"It saves lives, it saves taxpayer dollars, it frees up our emergency services, it reduces crime and it delivers positive outcomes for individuals and society," Ms Patten said.

A Victorian coroner recommended an injecting room trial in February and the police union, firefighters and paramedics all said they either supported it or wouldn't oppose it.

But Opposition Leader Matthew Guy says the Liberals and Nationals won't support an injecting room and there are other measures to consider.

Victorian Greens MP Colleen Hartland told ABC Radio the evidence from the Sydney injecting room shows it will save lives.