Nearly 1000 notices warning potential stalkers about their behaviour have been issued since new stalking and harassment laws came into effect earlier this year.

Police have laid 140 charges and issued 918 notices as of the end of August.

The new law came into effect in May and criminalises making unwanted, persistent, and repetitive intrusions into another person's life, causing serious psychological, social, and economic harm.

Police's Acting Director of Prevention, Inspector Natasha Allan, said those who engage in stalking and harassment should expect police action.

"We want people affected by stalking and harassment to know that they will be listened to, taken seriously, and supported. We encourage anyone experiencing this behaviour to report it to Police," she said.

"This behaviour is unacceptable and can have serious consequences for victims and their families."

Justice Minister Paul Goldsmith said the government was sending a clear message to stalkers.

"For too long this insidious behaviour went unpunished, yet victims were left with often long-term side effects," he said.

"Our government is committed to fixing the basics in law and order, and this is a prime example of a gap in the law which made no sense."

The new law carried a maximum penalty of five years' in prison.