Police Minister Judith Collins says the Government is looking seriously at legislation to restrict the sale of high-powered air rifles which are being blamed for two recent slayings in Auckland.

Police Sergeant Don Wilkinson died after he was shot with a FX Monsoon air gun while on a undercover drugs operation in 2008.

And now it has been revealed the same type of weapon was used in the slaying of Keith Kahi, 44, in the eastern Auckland suburb of Botany Downs nine days ago.

Earlier this year after John Skinner was found guilty of Mr Wilkinson's murder police said licensing high-powered air rifles as firearms needed to be addressed quickly.

Police Commissioner Howard Broad said a proposal to re-classify air rifles was considered before Mr Wilkinson's death and was before Parliament.

Under existing law anyone over 18 can buy an air rifle, including the high-powered FX Monsoon or similar air rifles, without a firearms licence.

The Police Association said the guns were weapons of choice among criminals who knew they would not be arrested if they were found with them. The guns were killers in the wrong hands and the law needed to be changed, said the association.

A bill to restrict the sale of the weapons had been before Parliament since 2005 but had not passed into law.

Mrs Collins said today it was a complex and technical issue and work being done by police on a change in the law was due to be put before her in the next week or so.

She told Radio New Zealand today technology had moved on since the original bill was introduced.

She said it was clear the old BB gun which was used by many people to learn firearms safety was vastly different from modern, gas-powered air rifles.

She said any change to the law would have to go through Parliament but it would be an "interesting" move to ban them when other high-powered weapons were available for hunters.

- NZPA