Image source, Press AssociationImage caption, The probation union cited pressure created by the early release scheme as it announced plans for industrial action later this month
Probation officers have voted to reject a 5% pay rise and take industrial action, citing growing pressure created by the government's prisoner early release scheme.
Members of Napo, the probation service union, voted to refuse overtime from 23 November - and could take strike action should the union "deem that option to be necessary".
Its general secretary Ian Lawrence said the service was "already in crisis" before the early release scheme came into force, which relies on probation staff monitoring freed prisoners in the community.
A Ministry of Justice spokesperson said the government had put forward a "strong offer" and was recruiting an extra "1,300 officers to significantly cut workloads".
They added that the government has "robust contingency plans in place" to ensure offenders "are still subject to the same rigorous supervision" in the event of industrial action.
Probation service unions have warned that officers have too many cases and the rate at which staff are leaving the profession has increased.
The service has come under renewed pressure in recent months as a result of the early release scheme, the union said, which the government introduced as prisons were dangerously close to capacity.
Seven-hundred eligible offenders originally sentenced to up to 19 months were released on 1 October, with another two groups of 650 prisoners released on 13 October and 10 November.
Another nine groups are expected to leave prison in the next seven months, with inmates who received longer sentences included in the later cohorts.
Some 250 prisoners serving more than 12 years are expected to be released on 9 June.
Napo's leader said staff had tried "desperately" to implement early release schemes introduced by the Labour government and previous Conservative government, but had been asked to do so with "inadequate staff and a lack of resources".
The government has said electronic tags and probation intervention will help to manage prisoners freed early.
The Probation Service uses electronic monitoring to track curfews and conditions of a court or prison order, with most of those eligible for early release now requiring tagging.
But a September report by His Majesty's Inspectorate of Probation (HMIP) found that almost half of electronic tags used to track offenders' movements were not fitted on time.
How the new prison release scheme will work - and number of inmates to be freed
