Police fear a group of young male bag-snatchers is on the prowl, hunting for women returning to their cars from grocery shopping at busy Auckland supermarkets.

And they warn it is only a matter of time before someone is seriously injured.

This week, two women have been confronted by bag-snatchers and police say that while the spike is not big in numbers, it is a major concern.

They believe the crimes are linked, as the same stolen car has been spotted at several bag-snatches and a robbery at a Manukau bar.

In 2008, a group of men stole Chinese businesswoman Joanne Wang's handbag at Manukau City shopping mall. They took off in a stolen vehicle, hitting Ms Wang, who died of her injuries two days later.

Sources say the notorious Killer Beez youth gang is at the top of the suspect list for bag-snatches in recent months.

Senior Sergeant Hirone Waretine would not be drawn on who is believed to be behind the thefts, but said it was likely to be a group of young male offenders working together and targeting the same spots.

"We are always worried about injuries to victims, absolutely. But what we're more worried about is there could be a group of young men running around Auckland targeting women. That could lead to something more serious."

On Sunday night, a woman had her bag snatched from her shoulder at Pakn'Save in Royal Oak.

She and her husband had been grocery shopping and were about to load their bags into their car when the thief struck.

Then on Monday night, a woman had a close call at Countdown in Greenlane. A man tried to open her passenger door to grab her purse but the woman - having been the victim of a bag-snatcher before - had locked her doors.

Mr Waretine said bag-snatchers tended to target women at supermarkets near motorways.

"Once they're out of there they have the ability to get to so many different places before we are on the scene.

"For example, from Countdown at Greenlane you can be on the Southern Motorway in under five minutes. From our point of view, that's what makes those supermarkets attractive."

Mr Waretine said bag-snatchers used a number of methods to get the goods.

"When filling up their boots, some women place their handbags in the boot. The offender runs up, gives the victim a push, takes the bag and runs off.

"They will also wait for the woman to get into the car and then open the passenger door and steal the bag off the seat. They'll even open the passenger door while the woman is stopped at traffic lights, or waiting to pull out of the supermarket carpark."

Mr Waretine said women needed to be vigilant with their bags.

"Put it under the seat, secure it in the car and lock all the doors - then unload your groceries."