The 120-bed jail was tempor' />

Wellington's Mt Crawford Jail is to reopen next month because of a recent increase in the national prison population.

The 120-bed jail was temporarily closed in June last year when it was considered surplus to requirements.

"It has become necessary for us to make use of the prison once more given the high demand for prison beds that is being experienced around the country," the Department of Corrections's acting assistant regional Manager Tony Howe said today.

The prison is one of the oldest prisons in the country, built in 1927 to replace the original Terrace gaol.

"While the prison is old the public can be assured that it has been maintained to ensure that the security of the site remains sufficient and that they will not be put at risk," Mr Howe said.

"We will begin transferring prisoners into the prison from July 6."

Mr Howe said that based on the 2008 Justice Sector Forecast, prisoner numbers were expected to reach 12,500 by 2018.

"Wellington Prison will be used to meet this increased demand as will double bunking which was recently announced by the Government in the budget."