A holding cell at Masterton District Court. There was a toilet and a drinking fountain, but no toilet paper.

With the court and police staff gone, a Wairarapa man locked in a holding cell knew he had been forgotten.

The only question was how long he would spend in a windowless cell with a toilet, a tap, a concrete slab for a bed, and a shoe for a pillow.

The answer was almost 48 hours, from Saturday morning till the courts reopened on Monday.

STUFF Masterton District Court, where the man was left over the weekend.

His only measure of time was by peering through a keyhole, down a hallway, to where a glimpse of light could be seen through a window.

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Police Minister Paula Bennett has called the blunder "unacceptable", as police begin an internal investigation. They have also notified the Independent Police Conduct Authority.

SUMMER REPORT/RNZ A man who was supposed to be released on bail man spent two days alone in a court cell after the police forgot he was there.

The man, who has name suppression after pleading guilty to drink-driving, was being held in the cell while his bail conditions were typed up, his barrister Susie Barnes said.

That should have taken 15 minutes on a Saturday morning.

But it soon became clear to him that court and police staff had gone home, and he was on his own.

PIERS FULLER/ FAIRFAX NZ Wairarapa area commander Inspector Donna Howard confirmed the incident, and said police had apologised to the detained man and his family.

"I knew they had forgotten about me," he said on Tuesday.

His home for the next two days was a tiny room. There was no toilet paper, no mattress, and no natural light.

"One of the things he said was, it was like torture. [There was] no way of knowing how long he would be there or when he would get out," Barnes said.

CAMERON BURNELL/FAIRFAX NZ Police Minister Paula Bennett said the error was unacceptable.

He spent the hours trying to sleep, trying to stay warm, and sometimes "screaming and yelling" in vain when he heard people outside.

There was no food, but there was a tap for water. The lights glared constantly.

Barnes visited him on Monday evening. "He seemed to be extremely vulnerable. He had been deeply affected by what had happened."

MURRAY WILSON/ FAIRFAX NZ NZ First MP Ron Mark described the case as "bizarre" and "very disappointing".

She intended to ask the judge to factor the ordeal into sentencing.

Wairarapa area commander Inspector Donna Howard said police had apologised to the man and his family.

"The priority is to determine how this happened and to continue to support [him]," she said.

JAMES IRELAND/STUFF Labour courts spokeswoman Louisa Wall wondered whether resourcing was a cause of the error.

"[After being discovered] he was immediately seen by a doctor and then returned home to his family."

According to a source, the court and police officer behind the blunder were "extremely distraught" about the error.

It was a "complete oversight" on their part, the source said.

UNACCEPTABLE, SAYS MINISTER

Police Minister Paula Bennett said what occurred was "unacceptable".

"I note that police have apologised to the man for the distress caused and continue to support the man and his family."

Human rights barrister Michael Bott said the incident was "appalling".

"Once you're placed in custody you're completely at the mercy of your custodians for your wellbeing, for food and water," he said.

"If this man ... required medication, something quite serious could have happened.

"I'm deeply concerned something like this can happen, where the jailers forget they have someone jailed. You'd think it shouldn't and couldn't happen.

"You can't just lock someone up and forget about them."

BIZARRE AND DISAPPOINTING

NZ First MP Ron Mark, who also lives in Carterton, said he had not heard directly about the incident from police, but it sounded like a shocking oversight.

"It just sounds bizarre.

"If it's true, it's clearly not good enough. They are very lucky, given the heat and temperatures of late, and no doubt they'll have some serious explaining to do.

"The people who are responsible for upholding the law and enforcing the law are the police, and that's in all manner of things. It sounds very disappointing."

Labour courts spokeswoman Louisa Wall questioned whether staff in the courts or police were being worked "to capacity", leading to the error.