Australian Border Force (ABF) officers will check people's visas on the streets of Melbourne this weekend as part of a police operation in the city's CBD, the Federal Government has revealed.

Key points: Border Force officers to check visas in Melbourne's CBD

Border Force officers to check visas in Melbourne's CBD The agency says people will not be targeted on the basis of race or religion

The agency says people will not be targeted on the basis of race or religion Part of a broader operation including Victoria Police and other agencies

Part of a broader operation including Victoria Police and other agencies Lawyer says Border Force involvement is "unprecedented"

Officers will be positioned at various locations around the city and will speak "with any individual we cross paths with", ABF regional commander for Victoria and Tasmania Don Smith said in a statement.

"You need to be aware of the conditions of your visa; if you commit visa fraud you should know it's only a matter of time before you're caught out," he said.

The statement said officers would work with "a diverse team of transport and enforcement agencies to target crime" in the CBD as part of Operation Fortitude.

"Tonight and tomorrow evening (Friday and Saturday) Metro Trains, Yarra Trams, the Sheriff's Office, Taxi Services Commission and the ABF will join Victoria Police as part of the inter-agency operation," the statement said.

"With a particular focus on people travelling to, from and around the CBD, the group of agencies will work together to support the best interests of Melburnians, targeting everything from anti-social behaviour to outstanding warrants."

ABF says people will not be targeted on basis of race or religion

A crowd of about 200 protestors gathered outside Flinders Street Station ahead of the ABF press conference. ( Jean Edwards )

More details were expected to be released in a press conference at 2:00pm but the event was cancelled.

Leading up to 2:00pm, demonstrators assembled outside Melbourne's Flinders Street Station to protest against the operation.

Ahead of that, a Department of Immigration and Border Protection spokesperson issued another statement saying: "To be clear, the ABF does not and will not stop people at random in the streets... the ABF does not target of the basis of race, religion, or ethnicity".

Victorian Police released a statement saying the public transport system would "be at its safest ... as a diverse team of transport and enforcement agencies take to the streets as a part of Operation Fortitude".

"There is a lot of truth to the saying that there is strength in numbers," Transit and Public Safety Command acting superintendent Campbell Mill said.

"From a policing perspective we will have Protective Services Officers, Passive Alert Detection Dogs, police, booze buses and automated number plate recognition vehicles deployed this Friday and Saturday night.

"While we are all separate organisations, we all have something in common — a responsibility to keep our community safe.

"In order to do that, we need to ensure that people are behaving appropriately."

Under the Migration Act, an officer may require a person who the officer knows or reasonably suspects is a non-citizen to show their ID or their proof of citizenship or visa.

'Will they only be stopping people with certain skin colours?'

Federal Member for Melbourne Adam Bandt said the operation was "worrying".

"The Border Force's plan to station their officers around the CBD and ask questions of 'any individual we cross paths with' is worrying, because it could threaten Melbourne's reputation as a welcoming city," he said.

"How will the Border Force distinguish between locals, visitors and visa holders? Will every person in Melbourne now be asked to show their papers as they move about the city? Or will they only be stopping people with certain skin colours?

"Melbourne shouldn't be a place where a government officer can stop you in the street and demand to see your papers because you're suspected of being a foreigner."

Lawyer Michael Bradley said the inclusion of the ABF in the operation was unprecedented.

"It looks like the Border Force is seeking to tie itself to a broader range of operations," he said.

"It doesn't change its jurisdiction or what it's able to do, but this seems to be more about public perception than legal reality."

Shorten questions timing of announcement

Opposition Leader Bill Shorten praised the Government's plans to crack down on crime and visa fraud, but said he was sceptical of the Government's decision to broadcast the plans prior to the operation.

"I do hope that any of these actions are done to try and protect Australian laws, to make sure that people are not overstaying their visas, to make sure that temporary guest workers are not being exploited," Mr Shorten said.

"If you're going to do a blitz, I don't know why you'd necessarily telegraph it to the media first."

Labor frontbencher Brendan O'Connor said he had not seen the details of the operation, but said he was worried about privacy.

"Any disproportionate deployment of Commonwealth officers should be considered carefully. I think we always have to balance security issues with rights of privacy," he said.