A man who held up a Palmerston North service station at knifepoint after being released from prison five days earlier, will spend another six years behind bars.

Brandishing a large kitchen knife and a box, Henry Tukino Maru, 38, robbed the Caltex service station, on the corner of Main and Ruahine streets, about 6.15am on January 30.

He was on parole at the time, having been released on January 25 after serving four years and nine months of a five-year jail term for aggravated robbery.

Appearing in front of Justice  Collins at the High Court at Palmerston North yesterday for sentencing,  Maru was sent back to prison for six years with a condition he not be released until he had served at least four years of the sentence.

When Maru was released from prison in January, a Parole Board condition stated that he was to remain at his supported accommodation between 10pm and 6am.

But five days later he entered the  petrol station armed with the knife and wearing a beanie, sunglasses, a pair of socks as gloves,  and a blue and white bandanna.

He demanded money from a female customer, and money and cigarettes from the male attendant, making off with  46 packets of tobacco and cigarettes, and about $319 in cash. No-one was injured.

Maru then ditched his disguise and hid the items under a gutter cover on Church St before returning to his Main St flat.

He then went on a shopping spree and bought two bottles of beer, a large container of glue  which he sniffed in Coronation Park  a magazine, a tin of lollies, clothes, a harmonica, and a small television.

Maru was arrested within four hours of committing the crime.

Justice Collins said Maru had mental health issues, and was addicted to drugs and alcohol.

"Unfortunately Mr Maru you are well known to the courts,'' Justice Collins said.

"You have been incarcerated in some shape or form for the past two decades.''

In March, Judge Gerard Lynch transferred Maru's sentencing  to be sentenced, to the High Court as he thought a term of preventive detention was appropriate, and only there could such a sentence be imposed.

Such a sentence would have meant Maru, who has a criminal record stretching back to 1992 that includes an unlawful sexual connection conviction, faced an indefinite prison term.

However, Justice Collins decided against preventive detention and opted for a sentence of incarceration with a condition that he must serve most of his sentence.

The owner of the  petrol  station, Jeremy Hoskins,  said it was a fair outcome for Maru.

"It's saving him from himself,'' Mr Hoskins said.

"It was a scary big knife used ...   he [the attendant] was nervous coming back to work but he's got on with it.''

Mr Hoskins' family has run service stations for about 30 years  but the  robbery was their first.

- © Fairfax NZ News