Police are investigating a third case of a child being approached by a man in the north of Auckland, further heightening concerns for parents.

Two 13-year-old girls were approached yesterday about 8.30am on Moffatt Rd, Red Beach, by an unknown man in a vehicle.

He offered to give the girls a ride as he was "going in the same direction as them."

Both girls declined and told their parents and police.

Police were already looking into an incident on Monday in Greenhithe where a 5-year-old boy, walking just metres behind his mother, was grabbed by a man.

The boy managed to break free and police were called.

And, about 3pm on Wednesday a nine-year-old girl was approached outside Red Beach School on Bay Vista Dr and offered a "lift" by an unknown man.

The girl declined and later told her teachers who called police.

In both cases in Red Beach the man was described as Caucasian and aged in his 40s with wavy hair. However the description of the type of vehicle driven differed in the two incidents.

Detective Senior Sergeant Brett Batty said inquiries were underway to establish any links between the incidents.

"The motives of the person or persons involved may well be innocent, but it is timely to remind people that these sorts of offers, though done with the best of intentions can often be misconstrued. We are keeping an open mind on these events.

"On a positive note in both cases, the offers of a ride from a stranger were firmly rejected.

"Police spend a considerable amount of time in our schools teaching children how to keep safe. In this case I am glad to say that these lessons have resonated and have been acted upon," he said.

He said an investigation into the incident reported in Greenhithe on Monday was continuing.

"North Shore Police have yet to determine the intentions of the male who had contact with a five year old boy. Police are following positive lines of inquiry in relation to this incident."

- © Fairfax NZ News