Prime Minister Jacinda Ardern will announce a law change at her post-Cabinet press conference today to make it easier for the police to stop gangs and criminal groups hiding their assets to avoid seizure laws.

Ardern will be joined by Justice Minister Kiri Allan and Police Minister Chris Hipkins.

She will also give a rundown of the week's events and gesture towards her trip to the United Nations General Assembly meeting in New York City later this month.

The proceeds of crime law change, revealed by the Herald this morning will amend the Criminal Proceeds (Recovery) Act outlined today and will allow police to target those with links to gang and organised crime figures who may be being used to shelter assets or cash which are the proceeds of crime.

The law change will also attempt to stop criminals using Kiwisaver accounts to shelter cash obtained through crime.

The law change will extend the application of the existing law to cases where the police believe that assets obtained through crime are put under the name of an "associate" to hide them and avoid them being taken.

The new law would force those with a link to a gang or crime figure who did not have the income to afford such assets themselves, to prove how they paid for them, or risk losing them.

National has already come out against the changes.

Responding to reports the bill was set to be introduced soon, the party's police spokesman Mark Mitchell told Newstalk ZB that while he supported seizing gang assets, the bill missed the bigger issue.

"They are not going to make any tangible impact right now on the amount of gang violence and gun violence that we're currently experiencing," Mitchell said.

• Law change to target hidden assets, cash gained through crime
• Ardern to travel to New York later this month

The Act Party called the bill a "U-turn".

The party's justice spokeswoman Nicole McKee said Labour had "finally accepted the logic Act has been promoting for years, if you want to tackle the gangs you need to hit them where they hurt – their wallets".

"If you take the profit out of gangs then you take away the incentive. If there's money to be made they'll find a way around law enforcement. If there's no money to be made they'll give up," McKee said.

Ardern may also face questions on a disturbing report aired on TVNZ's Sunday programme about people living in emergency and transitional housing in Rotorua.