Christchurch, March 10 NZPA - A teenager who murdered a Christchurch taxi driver was jailed today for nearly as long as his life so far.

Shannon David Boyes-Warren, 17, was sentenced in the High Court in Christchurch to life imprisonment with a non-parole period of 15 1/2 years of the slaying of Abdulrahman Ikhtiari.

His co-offender, 21-year-old Randall Legion Wiremu Brown, was jailed for 5 1/2 years with a non-parole period of three years eight months for Mr Ikhtiari's manslaughter.

Both youths pleaded guilty last month. They also admitted assaulting the taxi driver with intent to rob him. Their pleas came a few days before their trial was due to begin.

Mr Ikhtiari, an Afghan refugee, was described in court as "a man of courage and honour".

Crown prosecutor Mark Zarifeh told the court that Boyes-Warren stabbed Mr Ikhtiari to death with a 13cm bladed knife he carried around with him.

He said he Boyes-Warren and Brown were two young strong offenders against an older man on his own seated in a taxi.

The defensive wounds on Mr Ikhtiari's right arm and left leg showed that it was an ongoing and determined assault.

His glasses were dislodged and broken in the attack. The stab to the chest was the fatal wound.

The men displayed a lack of remorse when telling their associates about "shanking" a taxi driver after they returned to the city to continue drinking.

He said Boyes-Warren was 16 at the time and had a previous list of violence matters in the Youth Court.

Brown, 19 at the time, joined in the attempted robbery by restraining Mr Ikhtiari to prevent him from defending himself. He knew the knife was being used.

He had one previous assault with a weapon conviction, said Mr Zarifeh.

Defence counsel for Brown, Pip Hall, said Brown was a secondary party to both of the crimes.

The attempted robbery was well under way when Brown unwisely joined in the attack and restrained Mr Ikhtiari so he could not defend himself.

He could not see what was going on in the front seat, but knew there was a fight. His assistance was short lived, and his actions were not vicious.

He had genuine remorse and thought of the incident every day. He wanted to meet the family and was truly sorry for his actions.

Defence counsel Elizabeth Bulger said Boyes-Warren bore the burden of responsibility. He had written a letter to the family and his remorse and the feelings expressed were genuine.

He said he couldn't remember all of that night as he was too drunk.

He also would like to attend a restorative justice conference and would like the family of Mr Ikhtiari to see his video interview.

She said he had an unhappy childhood, with drugs and violence.

He did not know why he did it. It was not for money as he had money on him, she said.

Justice Christine French said there were 12 separate injuries on 39-year-old Mr Ikhtiari indicating the seriousness of the assault.

She said the victim impact report from his widow made very sad reading.

He was a man of courage and honour, a much loved husband and father of five, the judge said.

He was a refugee from Afghanistan and after four years apart was reunited with his family here, she said.

The judge said she was impressed with the letter to the family written by Boyes-Warren, and that it showed there was hope for him.

But there was a widespread concern in the community about the frequency of attacks on taxi drivers, and about the number of young people in the city carrying knives.