Image copyright PA Image caption The figures show 48 suspected or convicted criminals were freed by mistake last year

Prisoners are being released early by mistake at a rate of just under one every week in England and Wales, figures have revealed.

Ministry of Justice data obtained by the Press Association shows it has happened 505 times in the past decade.

Cases have included those in prison for murder and other violent offences.

Tory MP Philip Davies called the findings "disturbing", but the Prison Service said such incidents were "very rare" and becoming less common.

The figures obtained by the news agency show that 48 suspected or convicted criminals were freed by mistake in 2014-15.

In one case, Martynas Kupstys was released from HMP Lincoln while on remand for murder in August last year.

He was returned to custody after waiting at a nearby bus stop for three hours, and was later convicted.

Same surname

In an other example, a prisoner was freed from HMP Hewell, in Worcestershire, in July last year after an apparent mix-up involving another prisoner with the same surname.

This is nothing more than a shambles which puts the public unnecessarily at risk Philip Davis, Commons justice committee

He was taken back to jail the next day.

Mr Davies, a member of the Commons justice committee, said: "The first duty of the Prison Service should be protection of the public.

"These disturbing figures show that once a week the Prison Service release the wrong prisoner, and have done so for many years.

"This is nothing more than a shambles which puts the public unnecessarily at risk."

Shadow justice minister Andy Slaughter said it was further evidence of "the crisis in our prisons where overcrowding and violence are rife".

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The charity Victim Support said those affected by crime would be "alarmed and frustrated".

Director Lucy Hastings said: "We know it can be distressing and worrying when offenders are released from custody - releases made in error can make this many times worse."

The Press Association obtained the figures through a Freedom of Information request.

They show 41 people were wrongly released from prison and seven from court custody last year. This was one fewer than the previous year.

The number of releases in error has fallen by almost a third since 2009 and the vast majority are returned to custody very quickly Prison Service spokesman

Explosive substance

Over those two years, just under a quarter of the cases had been sentenced or charged over robbery or violent offences including assault and battery.

One was in custody on a firearms charge and another was being held for possessing an explosive substance.

Two of those released in 2014-15 had not been returned to custody by the start of December this year, including an alleged sex offender released from court.

There were three releases from HMP Manchester, one from HMP Belmarsh and one from HMP Woodhill, all high-security prisons, over two years.

HMP Bullingdon in Oxfordshire has the highest number of such releases over the same period with 10.

'Top priority'

The Prison Service said public protection was its top priority.

A spokesman said: "These incidents are very rare but we are not complacent.

"The number of releases in error has fallen by almost a third since 2009 and the vast majority are returned to custody very quickly.

"The Prison Service investigates each incident and they are reported to the police for further action."