It's an early winter's evening and emergency services are scrambled after a report that a car has plunged into a river.

Police, fire, ambulance staff and the Taranaki Community Rescue Helicopter are dispatched to the Awakino Gorge just after 6pm, where a male caller claims a vehicle has crashed off the notoriously dangerous section of State Highway Three.

But the May 20 call later turned out to be a hoax - one that cost taxpayers more than $20,000, wasted the valuable time of emergency service volunteers and could have resulted in an unnecessary death, police SAR coordinator Senior Constable Vaughan Smith said.

"It could have potentially cost a life."

"If something came up in their own area that was health related and an emergency, those people are now at risk because there is no service to look after them.

"They are a key asset to those communities and without them lives can be lost."

The caller claimed he managed to escape from the vehicle after his mate failed take a bend near the tunnel, crashed down a bank and plunged into the river.

The chopper flew the length of the river searching for signs of the car or its occupant, while police, fire and ambulance staff from Taranaki, Pio Pio and Te Kuiti scoured the bush-covered banks.

Searchers returned the next day and spent hours combing the area.   

Smith confirmed a thorough search of both the Awakino and Mōkau rivers, the road between the two settlements and the townships had proved fruitless.

"There was no vehicle located in either river," Smith said.

Police had located the man who made the 111 call and had spoken to him, but he maintained there was a real emergency.

"They said it was a legitimate call and gave circumstances which could not be confirmed."

Smith said there were no independent reports of any missing persons or vehicles, and police did not believe the report was genuine.

All emergency calls had to be taken seriously until they could be proven otherwise but he condemned anyone making fake reports.

"To say it's foolish is at the minimum level.

"How would you like it if you or a member of your family were in dire need of help and somebody was out working on a job that doesn't exist - it was just a joke?"

While no charges had been laid, inquiries were ongoing and there was potential they could be in the future, Smith said.