A man who kidnapped another and subjected him to "degrading and dehumanising torture" has been jailed for eight and a half years.

On the second day of a trial earlier this year the man pleaded guilty to kidnapping, two charges of wounding with intent to injure, assault, three of threatening to cause grievous bodily harm and injuring with intent, relating to two days in February, 2016.

During the ordeal the man stripped another man of his clothes, beat him, put a dog collar round his throat, hog-tied him with an electrical cord, blindfolded him, urinated over him and burned his genitals with a cigarette.

He also admitted perverting the course of justice about a year later.

The man was sentenced in the High Court at Whangārei where Justice Matthew Muir granted him and the victim name suppression.

However, as Justice Muir read out details of the victim's ordeal he described the terrifying attack as "degrading and dehumanising torture".

The tied-up victim was dragged around a rural Northland house causing him to suffer carpet burns.

The offender also attached a dog chain from the dog collar to the victim's hands, which at times caused breathing problems. The abusive kidnapping was an act of revenge, which the man now acknowledged had been based on rumours only.

A year later the man tried to pervert the course of justice by making a phone call to a woman asking her to back him up with his upcoming court case.

Justice Muir received a hand-written letter from the man and accepted he was truly remorseful. The man had also wanted to be part of a restorative justice programme but it did not go ahead.

"This was a sustained, violent and degrading assault," Justice Muir said.

A report said the man was at high risk of reoffending, which was considered to be escalating, he had never been in employment and had long-term criminal connections. He also had a history of methamphetamine and cannabis abuse.

On the charge of kidnapping and seven charges related to it, the man was sentenced to seven years and two months in jail.

For perverting the course of justice he was sentenced to 16 months' jail, to be served cumulatively.

His total jail time was eight and a half years and he was ordered to serve a minimum of three years and seven months on the kidnapping charge.