Fourteen inmates are understood to have been freed from Devon’s prisons on Tuesday under the government’s early-release scheme to ease overcrowding.

The Prison Officers’ Association said it believed 10 would be let out of Channings Wood prison in Newton Abbot, and four from Exeter.

A further 31 are expected to be released from Portland prison in neighbouring Dorset.

Dartmoor prison was closed earlier this year in what is claimed to be a temporary move, because of high levels of radon gas at the Napoleonic-era jail. Its inmates have been relocated to other prisons across the country.

Over the next two months, around 5,500 prisoners nationally will be released after serving 40 per cent of their sentence, rather than the usual 50 per cent.

The rest is served in the community under the supervision of the probation service. This change will be reviewed after 18 months.

Sex offenders, and people convicted of serious violent offences, domestic violence or terrorism are not eligible for early release under the scheme.

The Ministry of Justice (MoJ) said the prison population of England and Wales stood at a record high of 88,521 last week, just 1,098 places below maximum capacity.

Longer sentences, failure to hit prison-building targets, and higher numbers of inmates being recalled from parole have contributed to the rising numbers of people in prisons.