Forty-five people have been convicted of a serious violent offences since the "three strikes" legislation came into effect this year.

Under the new law, which came into effect on June 1, 40 violent offences attract a strike upon conviction.

After a third strike, a maximum sentence with no parole will be handed down.

Police Minister Judith Collins said today that 45 people had been convicted of a first-strike offence, of whom five had been sentenced.

There had been no convictions for second-or third-strike offences.

Ms Collins said the three-strikes law meant the worst repeat violent offenders would not receive parole.

"Parole is a privilege that must be earned. It should not be granted to those who demonstrate total disregard for the law by continuing to commit serious violent offences despite warnings," she said.

"Offenders who remain in prison to serve their full sentences will not have the opportunity to commit further crime. This means there will be fewer victims, and that is an excellent outcome."