A rural Canterbury police officer feared he was going to be stabbed in the head after being confronted by a teenager armed with a bayonet and a knife.

The incident, near the North Canterbury town of Culverden about 9pm on Saturday, came only a day after a Waikato rural police officer, Constable Perry Griffin, was brutally attacked by five men in the coastal town of Kawhia after going to make an arrest on his own.

The Culverden incident ended after one of the officers Tasered the man, who was then arrested.

Senior Sergeant Malcolm Johnston, of Rangiora, said two officers were confronted after going to a farm to inquire about what looked like a pit bull dog running loose in Culverden Rd.

He said that as the officers drove on to the property they were approached by a young man.

At first they thought he was a farmhand, but as he got closer they realised he was armed with a bayonet and large knife.

The man was agitated and aggressive, Johnston said.

The officer in the passenger seat had his window down and feared he would be attacked as the man came within a metre of his door.

The bayonet was about half a metre long.

"[The officer] thought he was going to stab through the window," he said.

The officer opened his door to provide a buffer between himself and the offender, while the other officer got out of the car and pulled out his Taser.

Johnston said the officer repeatedly warned the man to drop the knife before Tasering him.

It was only by chance there were two officers in the car at the time, or it could have been a lot worse, he said. The officers had met at the Culverden police station and gone in one car to the farm.

Johnston said it was a "sober message" for police staff that rural New Zealand was not "safe as houses".

The officers did not have time to phone for backup, he said.

"There have been so many attacks on police. You just don't know when something is going to go wrong,'' he said.

"These two officers would have had their heads taken off. The good thing is, the guy is still alive."

He said that if police did not have a Taser, it was likely the offender would have been shot.

Johnston said one officer was on holiday but the other was back at work and doing OK.

An 18-year-old was scheduled to appear in court today charged with assault and possession of an offensive weapon.

- © Fairfax NZ News