Prime Minister John Key says the Taito Phillip Field saga reflects very badly on Parliament, but is an isolated case.

Field was found guilty in August of 26 charges of bribery, corruption and obstructing the course of justice.

In the High Court at Auckland on Tuesday, Justice Hansen sentenced Field to four years in prison on the 11 corruption and bribery charges and two years on the 15 charges of obstructing the course of justice.

John Key says six years is not an insignificant sentence, and he'd like to think that will help New Zealand's reputation as not tolerating corruption.

He says the Field case reflects badly on the Labour Party, and it was only because of pressure from National while in opposition that Field was ultimately held to account.

The judge told him that Taito Phillip Field had put his private interests ahead of his public ones by granting immigration favours to eight people in return for free labour on five properties he owned.

Some of Field's actions, Justice Hansen said, had threatened the foundations of democracy, and he had betrayed the trust of the people he represented.

He had cynically used the adulation Thai nationals felt towards him for his own financial gain. He had given them an opportunity for a new life, they revered him for it and he used that gratitude.

The judge said Field must have known that the tradesmen's willing assistance saved him tens of thousands of dollars, but when his public and private roles came into conflict his private interests won.

Little emotion shown at sentencing

When taken from the court Field was holding a bible; supporters called out to him to be strong, and told him they loved him. He showed little emotion as the sentence was delivered but had earlier been wiping his eyes.

Last Friday, he publicly apologised for the circumstances leading to the trial, but denied any wrongdoing, saying that the truth was still to be exposed.

At one stage the sentencing hearing was interrupted when a man told the court the case was an act of treason. He was taken away by the police.

Defence lawyer Paul Davison said he thought the sentence was tough and longer than he submitted was appropriate.

He said he had hoped for a sentence in the vicinity of four and a half years.

Mr Davison hasn't ruled out an appeal.

Reaction to sentence

As his punishment was handed down many of his supporters started sobbing.

Outside court his wife Maxine Field said she was disappointed with the sentence but accepted the law was the law.

She says she is heartbroken he will spend the next six years behind bars.

She tearfully maintained her husband never intended to do anything wrong and had a 'clean heart'.

The Speaker of the House, Lockwood Smith, has expressed sadness that Field has been sent to prison but says it shows that all MPs are accountable for their actions and that no one is above the law.

While Opposition spokesperson on immigration, Dr Smith pursued Field's handling of the immigration cases at the heart of the corruption convictions.

The Labour Party also says that the sentence shows that all New Zealanders are equal under the law. Field has been judged by his peers, says deputy leader Annette King, and must now serve the sentence handed down.

Case 'exhausting and difficult'

Crown prosecutor Simon Moore has described the case as "extraordinarily exhausting and difficult".

He said the case had unique aspects which made it one of the more challenging sentencing decisions to confront a judge.

Mr Moore says those aspects included the fact it was the first time a member of parliament had been prosecuted in New Zealand for bribery and corruption.

Another was the position Field held and the fall from grace from someone who had served the community well.