The Department of Corrections is investigating the escape of an inmate from Mt Crawford Prison.

Three prisoners were caught on a roof at the Wellington facility yesterday morning trying to jump over a prison wall. A fourth had already managed to scale the wall but police caught him less than an hour later.

The prison is one of the oldest in the country and had been mothballed but was reopened in July because of the need to house prisoners. At the time, the Department of Corrections assured the public that while the prison is old, it is has been maintained to ensure sufficient security.