Footage taken from a camera attached to a sniffer dog has given the public a "unique insight" into police attempts to stop contraband entering the prison system, a South Australian minister has said.

A GoPro camera was fitted to a sniffer dog as it performed a "sweep" of Mount Gambier Prison with its handler.

Of the 79 visitors checked by sniffer dogs at the prison, 18 people were turned away, seven were banned for 12 months and one person was arrested for attempting to bring drugs inside.

The Government said those turned away gave a "positive indication to drugs by the dogs" but no substances were found.

Correctional Services Minister Tony Piccolo said the unit had five handlers and five dogs and, since it was launched in 2014, had undertaken 185 search operations, including 1,868 cell searches, 2,054 prisoners searchers and 1,585 visitor searches.

"It's about reducing the risks presented by criminal gangs attempting to take drugs, weapons and other contraband into South Australian prisons," he said.

He said telecommunications at the prison were shut down ahead of the search so prisoners could not warn visitors about the operation.

Smuggling contraband into a SA prison attracts a maximum jail sentence of five years.

Prisons above capacity to the 'end of the decade'

The State Government has predicted its prisons would remain filled beyond their capacity until the end of the decade.

Mr Piccolo today told a parliamentary hearing the state recorded an all-time record number of 2,772 prisoners earlier this month.

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Based on current trends, that number is expected to increase to 3,024 daily average prisoners in 2018-19.

Liberal MP John Gardner asked Mr Piccolo if that would be above the SA prison system's forecast non-surge capacity of 2,997 prisoners in 2018-19.

"In the absence of any legislative reforms, or in the absence of any new build or expansion, yes that is correct," Mr Piccolo said.

There are currently 2,773 beds in the prison system, which is expected to increase to 2,885 beds in the next financial year as more beds are added, and rise to 2,997 beds in 2017-18.

Mr Piccolo said he would rather investigate adding more beds to existing prisons rather than build a new jail.

He said the Government was trying to reduce prisoner numbers by placing more people in home custody with monitoring bracelets on their ankles.

"That's more of a case of making sure that only those people who need to be in jail will be in jail, and those people who don't pose a risk can be managed in other ways," Mr Piccolo said.