The son of a prisoner who has spent 12 years in jail after robbing a mobile phone says his dad's controversial sentence is "so cruel and unfair" after being turned away from seeing him following an error.

Thomas White, from Bury, was given an imprisonment for public protection (IPP) sentence in 2012 following the crime.

IPPs were a type of indeterminate sentence courts could impose after being introduced by the Criminal Justice Act 2003.

Nearly 3,000 prisoners, many of whom are very low-level offenders, remain in prisons today on such sentences.

Thomas, who is said to have a history of committing petty crimes, was ordered to serve a minimum of two years, only a few months before IPPs were abolished.

But after more than a decade behind bars, there is no immediate prospect of him being released.

Thomas is behind bars at HMP Manchester and was supposed to meet his son Kayden, 14, last week which would only be their second reunion.

In April, Kayden was able to see his dad for the first time, thanks to an intervention from Lord David Blunkett, the former Home Secretary who introduced the controversial sentence.

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After the visit block was overturned, Kayden was told he could have monthly visits with his dad.

But last week when Kayden and his grandmother Margaret White went to HMP Manchester, an error meant that the visitation could not go ahead.

However, the visit has been rearranged for this weekend.

Kayden said: “It’s been nearly two months since I last saw my dad.

"We have so much lost time to catch up on. This whole thing is so cruel and unfair.”

When they had their first visit eight weeks ago, there was not a dry eye in the room.

Kayden gave his dad, who is “the best hugger in the world”, a hug which lasted for many minutes, and they spoke of life after prison and of one day going fishing together.

Thomas' mother Margaret White, who is also Kayden's grandmother, said: “Once again, we have been let down by a broken system.

“In what world is it fair for a 14-year-old child to be turned away on the prison steps from seeing their dad?

"He was so excited for this visit. We are resilient but this is getting too much.”

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Thomas’ family are urgently asking for him to be transferred to a psychiatric hospital where he can access appropriate mental health treatment after receiving a diagnosis of paranoid schizophrenia.

Lord Blunkett and Bury North MP James Daly have both pledged their support to the family.

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Two hospitals in the Greater Manchester area have reportedly rejected a bed for Thomas in the last six months despite his worsening mental health.

The Ministry of Justice said it is unable to comment on the matter before the General Election, but in February a spokesperson said: “We have reduced the number of unreleased IPP prisoners by three-quarters since we scrapped the sentence in 2012, with a 12 per cent fall in the last year alone where the Parole Board deemed prisoners safe to release.

“We have also taken decisive action to curtail licence periods and continue to help those still in custody to progress towards release including improving access to rehabilitation programmes and mental health support.”