A spring once described as New Zealand's best kept secret is becoming a target of thieves.

Every two to five days a vehicle is being broken into at The Blue Spring at Te Waihou Walkway near Putaruru in South Waikato.

Putaruru police Sergeant Daniel Peat said there had been a steady climb since Christmas of vehicles being broken into at the popular tourist attraction's Whites Rd and Leslie Rd car parks.

LUKE KIRKEBY/ STUFF Perth's Dion and Pauline Jacobs say it's disappointing the Blue Spring near Putaruru has become a hot spot for thieves.

"Traditionally we tend to have one a month. At the moment it is one every two to five days," he said.

READ MORE:

* Putaruru Blue Spring - NZ's best kept secret?

* Iwi concerns delay cafe plan for Putaruru's Blue Springs

* Restaurant, function centre, approved for Putaruru Blue Spring

* Taking water diminishes Blue Spring's mana, say local iwi

Peat said tourists who were leaving valuable items unattended and in plain sight, were being targeted.

SUPPLIED Swimming was banned at the Putaruru Blue Springs after a huge influx of tourists caused significant damage.

"Since Christmas there have been five vehicles broken into in Leslie Rd and three in Whites Rd," he said.

"All have been tourists and all but one have lost their passports in those thefts."

He said it was a major concern, not only for visitors, but for the community as a whole.

"The offenders are effectively smashing car windows and dragging suitcases out," he said.

"Over $3000 worth of property was taken from one vehicle. It is an exceptionally bad look for our community."

When approached by Stuff, Blue Spring visitors expressed shock on hearing thefts had been taking place.

Shanghai tourist Ken Ye said it didn't even cross his mind to remove valuable items from his car.

"We have suitcases in our car but we haven't put them out of sight. I thought it was safe here," he said.

Dion and Pauline Jacobs, who are originally from New Zealand but have been living in Perth for six years, said it was disappointing.

"We have come home for a holiday and thought we would do this walk. It's a bit sad this is happening because it is beautiful," Pauline said.

Peat said police were working to combat the issue.

"All have had significant luggage type items in view, laptops, cameras, and things like that which is quite understandable given that they are travelling but it is something that we are focussing on and putting quite a lot of resource into to try and identify who the offenders are," he said.

"There are a few possibilities and tactics that we are utilising out there but I don't want to go too much into what those are."

South Waikato District Council communications manager Kerry Fabrie said the council was looking into installing cameras at the car parks.

'Lock it or lose it' signs are already in place.