An extra 1,400 beds for the state's jails have been announced by the New South Wales Government under a plan that includes reopening old jails and commissioning what it calls "rapid-build" projects.

In the July budget for 2016-2017, the Government announced 2,800 extra beds over the next three years as part of a goal to increase capacity by 7,000.

On Friday, Corrections Minister David Elliott visited Wellington jail in the state's central west to announce the construction of a new, separate high-security facility there.

It will have 400 beds and will be constructed under a rapid-build model that will see it completed within 12 months.

Today the minister added to that announcement, releasing details for new beds at six jails, among other developments across the state.

360 extra beds for Nowra Jail on the south coast

360 extra beds for Nowra Jail on the south coast 240 extra beds at Emu Plains jail in Sydney's west

240 extra beds at Emu Plains jail in Sydney's west 250 new beds at Bathurst in the state's central west

250 new beds at Bathurst in the state's central west 400 new beds at Kempsey on the mid north coast

400 new beds at Kempsey on the mid north coast 480 extra beds at Junee in the Riverina

Berrima jail in the Southern Highlands will reopen next month, with 75 minimum security prisoners.

Another prison being reopened is Unanderra at Wollongong which will have 60 inmates.

"We can't sugar-coat the fact that NSW prisons have been under stress, so this investment will see us address this capacity issue," Mr Elliott said.

Adult prison population increased 12 per cent since last year

As of January this year, the adult prison population was more than 12,000 — a record high and a 12 per cent increase on the year before.

"This is not money that any politician wants to spend," the minister said.

An image of the rapid-build prison design for Wellington jail. ( Supplied: NSW Government )

"If I had my way this money would be spent on schools, hospitals, roads and on making NSW much more attractive to foreign investment."

The Government will also expand Cessnock jail by 1,000 beds under a rapid-build model, a move that has been slammed by some members of the community.

Earlier this week, hundreds of Cessnock residents turned out to a meeting to oppose the decision.

A juvenile detention centre at Lidcombe will be "hardened" into an adult jail for 90 women, the Government said.

"On a proportional basis, female incarceration has increased faster than male incarceration," Corrective Services commissioner Peter Severin said.

The minister emphasised his commitment to the rehabilitation of offenders, despite a decision earlier this year to cut the number of teachers in jails from 152 full-time positions to 20.

The Government is creating 60 new roles, but is not clear whether they will require teaching degrees.

"We have to double the number of people doing literacy and numeracy skills in prisons — at the moment we have prisoners doing music appreciation," Mr Elliott said.

"Hopefully some of the people who are doing the jobs now will reapply for the new positions."