Hard core extremists will be housed in a new 'mini-max' jail within Goulburn's Supermax in the Southern Tablelands in a move the government says will prevent further radicalisation within NSW jails.

The NSW government will spend $47 million over three years as part of next week's budget to fund the operation, to be known as Supermax II.

"We don't want to see people already behind bars subject to radicalisation," Premier Gladys Berejiklian said outside Silverwater Prison on Sunday.

"If you are going to engage in activity which is going to try and convince others and manipulate others to do so, you will be sorted out."

The new facility will house 54 inmates and is part of an overhaul that will include soundproofing and audio and CCTV upgrades to monitor visits from family and friends and improve intelligence gathering.

The government is aiming to have it completed by the end of 2018.

Goulburn SuperMax jail.

Corrective Services NSW Commissioner Peter Severin says the number of prisoners on terror related charges has more than doubled since 2013, with 33 out of 45 prisoners in custody over terror related offences at the high security jail.

"It is about making sure that we don't have a situation where people have unduly influence over others across the system," Mr Severin said.

"We are dispersing them in a way that will allow us eventually to get them to disengage.

"By centralising those who have the potential to cause the most harm, we actually keep the rest of the system safe."

Mr Severin said over the last three years up to five inmates have been radicalised in NSW prisons.

"It is a small number. Nevertheless what we need to do is ensure it remains that way."

The 16-year-old Supermax High Risk Management Correctional Centre, which houses some of Australia's most notorious criminals including serial killer Ivan Milat, is also expected to nearly double in capacity, from 45 inmates to 75.

Immigration Minister Peter Dutton applauded the plan.

"So long as the way in which these prisons are designed and configured doesn't mean all the terrorists are together in each others company reinforcing each other's ideology," he told Sky News.

The NSW prison upgrade is one of a series of measures across the nation to stamp out the growing threat of terrorism.

Queensland announced on Sunday it will get 50 extra police officers to help authorities try to eradicate the "menace" of terrorism by relying on preventative tactics and intelligence techniques.

"I asked specifically for an increase in our numbers to deal with the ever-growing threat of terrorism, and the government has delivered," Queensland Police Commissioner Ian Stewart said.

Meanwhile the federal government is seeking co-operation from social media companies, such as Google and Facebook, to help decrypt communications between terror groups.