Beware recording intimate encounters because anything put online can go viral, an internet safety expert says after a video of three Blenheim women was posted on Facebook.



Two of the women in the intimate recording said in posts on their Facebook pages that they were taking legal action and getting psychiatric help after the video spread.



Marlborough area commander Inspector Simon Feltham said two of the women had contacted police because they were concerned about the attention they were getting in relation to the video.



The video of the women, believed to be aged in their late teens and early 20s, was circulated on Facebook last week.



The video, lasting about 90 minutes, is understood to have been shot with a webcam in a bedroom.



A Blenheim man said he heard about the recording on Thursday after friends posted a link to a website that contained the video.



"All of a sudden, it was everywhere," he said.



The video was removed from the website within 30 minutes, but it had been downloaded and re-posted to new websites, the man said.



Within a few hours, he had seen at least 50 Facebook posts that mentioned the video, including posts by friends in Australia.



"It just went viral," he said.



"Everyone was talking about it."



Netsafe operations manager Lee Chisholm said people needed to be aware that anything they put online could be copied and redistributed.



She said people performing sexual acts for money on webcams was not unheard of and a documentary called Webcam Girls was aired on TV3 last week.



Anyone who performed on a webcam should be aware they could be recorded, she said, though there had been no reports in New Zealand of webcam recordings of sexual acts being used illegally.



"Anything you post, send or write can be copied and redistributed anywhere online," she said.



"It's something to be very aware of."



Feltham said police were looking at people's behaviour after the video was released to try and establish whether an offence had been committed, such as harassment or intimidation.



Police were not investigating the circumstances in which the video was made, he said. The women were unhappy the video was out there.



"They want the attention on them to stop, but there's nothing we can do about that," Feltham said.



Police could not act unless an offence had been committed.



The women could not be reached for comment.



The Department of Internal Affairs deals with censorship issues relating to people using the internet to share objectionable material.



A spokeswoman said objectionable material had to be proven to be "injurious to the public good" and pornography did not usually fall under that definition unless it was extreme.