An outreach worker linked to a medically supervised safe injecting room in Melbourne's inner east is among a group of people now charged with trafficking the drug heroin.

Key points: Police have charged five people with trafficking with more expected to be charged

Police have charged five people with trafficking with more expected to be charged Police said they did not allege any offences had occurred inside the safe injecting room

Police said they did not allege any offences had occurred inside the safe injecting room The government said allegations against staff employed at the North Richmond Health Service were "very serious"

Victoria Police arrested eight people on Thursday afternoon as part of an ongoing investigation into drug trafficking in the Richmond area.

Officers executed a number of warrants at residential properties in Burnside Heights and Richmond.

Heroin and cash were also seized at the properties.

Among those arrested were:

A 49-year-old Richmond man who was arrested in Victoria Street, Richmond

A 49-year-old Richmond man who was arrested in Victoria Street, Richmond A 36-year-old Brunswick West woman who was arrested at a health facility in North Richmond

A 36-year-old Brunswick West woman who was arrested at a health facility in North Richmond A 43-year-old woman and a 51-year-old man, both from Burnside Heights, who were arrested in Gardner Street, Richmond

A 43-year-old woman and a 51-year-old man, both from Burnside Heights, who were arrested in Gardner Street, Richmond A 42-year-old man and a 42-year-old woman, both from Richmond, who were arrested in Egan Street

A 42-year-old man and a 42-year-old woman, both from Richmond, who were arrested in Egan Street A 35-year-old Richmond man who was arrested in Murphy Street

A 35-year-old Richmond man who was arrested in Murphy Street A 40-year-old Richmond woman who was arrested in Elizabeth Street

Officials from the Department of Health and Human Services met overnight to discuss allegations two workers at the controversial safe injecting room in Richmond had been dealing drugs.

Police said the 49-year-old Richmond man and 36-year-old Brunswick West woman worked at a health facility in North Richmond, which the ABC understands is housed in the same building as the state's medically supervised safe injecting room.

The Richmond man was charged with trafficking a drug of dependence, while police said the Brunswick West woman was released and expected to be charged on summons for trafficking a drug of dependence.

It is understood the two people are outreach workers at the health clinic but it is not clear how much overlap this service has with the safe injecting room.

Four others — the 43-year-old Burnside Heights woman, the 51-year-old Burnside Heights man, the 42-year-old Richmond woman and 35-year-old Richmond man — were charged with similar offences.

Of the five charged, all have been granted bail except the 35-year-old Richmond man.

The 40-year-old Richmond woman was released, pending enquiries.

In a statement, police said they were not alleging that any offences occurred inside the health facility.

A two-year trial of the safe injecting room was declared a success by the State Government earlier this year. ( AAP: Julian Smith )

'Very serious' allegations

Acting Mental Health Minister Luke Donnellan said the allegations against staff employed at the North Richmond Health Service were "very serious".

"Such behaviour is completely unacceptable and will not be tolerated," he said.

"We're doing work with the Department of Health and Human Services to see what action we can take separate from that which the police are currently working through.

"The Government will swiftly investigate this matter and take action."

He said as the matter was currently under investigation by Victoria Police, it would be inappropriate to comment further.

A long-time advocate of the safe injecting centre, Reason Party leader Fiona Patten, said it was important to note that none of those arrested were directly employed by the centre.

She said closing it was not the answer.

"We need to keep acting there, we need to keep improving the services," she told ABC Radio Melbourne.

"We need to look at how this happened and what changes need to be made to ensure that this never happens again."

Ms Patten said "every possible drug and alcohol service for Richmond" is at the centre and that may be part of the problem.

"I think maybe we need to look at relocating some of those services so we don't have every single person who is recovering, who's using, all congregating at the same place," she said.

The Opposition spokesman for police David Southwick said the safe injecting facility needed to be fully investigated.

"How deep does this run? How often is this going on? Are drugs being sold within the premises? Are other people involved? There are a number of questions that require immediate answers," Mr Southwick said.

Police said the arrests came as part of Operation Sievers, a three-month investigation targeting drug trafficking.

Acting Superintendent Kelvin Gale said police would continue to work to disrupt the supply of drugs in the area.

"The trafficking of drugs causes significant harm in the community, which is why we are absolutely committed to arresting these offenders and putting them before the court," he said.