Himatangi Beach is an especially popular spot for people with their vehicles.

Irresponsible four-wheeled behaviour on Manawatu and Horowhenua beaches is continuing to keep police unnecessarily busy.

Police are urging quad bike and ATV riders to treat the beach like a road, as people overload their bikes, speed and neglect to wear helmets over the holiday season.

The call comes after a crash on Monday, when two people were injured in a quad bike crash on Foxton Beach. Both were taken to Palmerston North Hospital with moderate to serious injuries.

Central District command centre Senior Sergeant Steve Thomas said there were "far too many" incidents involving ATVs and quad bikes on beaches.

Thomas said it was an ongoing theme over the summer, as people ignored the rules while on their bikes.

The danger of the irresponsible behaviour was also inflamed by the higher number of people on the beaches.

"A lot of beaches actually have speed limits; people need to be more mindful," he said.

"You've just got to remember, would you ride that on the road?"

It is an especially pertinent issue for police officers in the Horowhenua region, who look after Waitarere, Himatangi and Foxton beaches.

Himatangi Holiday Park owner Reuben Newbury said riding on the beach was a major drawing point for Himatangi Beach over the summer.

"There's heaps of them, that's why they come. They use them to get out on to the beach and get into the dunes.

"We have site holders that come to holiday here. They have to register their bikes and wear the proper gear."

With dunes and forests to negotiate on their motorbikes, both families and enthusiasts make the most of the beach. Specifically, a bowl in the dunes attracts many riders.

"From what I've seen, it's a good family activity.

"With mum and dad, and a trail of kids behind them, they putt around."

Police often stopped bikers to ensure their quads were registered, and that they were abiding by the road rules.

Foxton Beach Surf Life Saving Club captain Joss Urbahn said: "As far as we are concerned the beach is a road and all the road rules apply. We have speed limit signs on the beach at Foxton."

Foxton Volunteer Beach Wardens group co-ordinator Ross Brannigan said the past couple of days had been some of the busiest they had seen.

He said behaviour in vehicles had been good this summer and the presence of the wardens and police generally kept behaviour in check.

"It's always been the aim that people can take their families down there in a safe environment; it's for recreation, not a racetrack."

In the early 2000s they had some "horrendous times" but bylaws and signage had been changing that.

A patrol group has been set up in Himatangi this summer too.