He was even more shocked when he was handed a notice from NSW Police saying he was barred from Sydney Olympic Park for six months.

An image of the intimidating-looking document, handed out at Saturday’s Above & Beyond dance music festival, is sparking a massive backlash against police as it spreads on social media.

The picture, which has been shared thousands of times, has stoked an angry reaction among music fans who say it is an abuse of police power.

NSW Police told news.com.au this afternoon the festival-goer was handed the notice not because of being stopped by a sniffer dog, but because of “bad behaviour”. He also didn’t have a ticket for the event, the police alleged.

However, a spokeswoman for anti-drug dog campaigners Sniff Off, who saw the booted-out music fan shortly after was handed the notice, rejected the police version of events.

She said the festival-goer and his four friends had been arguing with the officers who conducted the strip search, which is why he was given the notice.

Greens MP David Shoebridge told news.com.au his office had been contacted by five other festival attendees who were refused entry or kicked out simply because a police sniffer dog approached them. When police searched those who had been approached by the dogs, they had nothing incriminating on them.

He said he has heard of “many more” music fans who were penalised on the night, which he called an “appalling attack on civil liberties”.

“We’ve now seen two appalling attacks on civil liberties in the one night,” he said. “People have been refused entry to a cultural event due to the judgement of a dog and then the police have doubled down on that by banning them for the entire Olympic Precinct for six months.

“It is a new, noxious development.

“We have known for over a decade, that these dogs get it wrong up to 75 per cent of the time. But, up until now, people haven’t been punished for them getting it wrong.”

Above & Beyond tickets cost upwards of $128. News.com.au has tried to contact the festival organisers to ascertain whether those wrongly tested and booted out would be offered a refund.

However, a spokeswoman for Sniff Off said the organisation was now “seeking legal counsel” on behalf of those affected to challenge what it calls an “abuse of police powers”.

Thousands shared and commented on a picture of the six-month ban notice on social media — with many accusing the police of being too harsh.

“NSW cops are the definition of the fun police,” said one Facebook commenter.

“This is a clear abuse of power,” wrote another.

Police have not released any information about how many people, if any, were arrested on drugs charges at Above & Beyond. Thirteen people were ejected for drunkenness.

Mr Shoebridge said the “extraordinarily strong” online backlash against the notices had effectively silenced NSW Police.

“This the first time ever that I’ve seen the police not put out a press release or a social media post after a drug operation at a music festival,” he said.

“They have been utterly silenced and I think they have been shamed into silence.”

Before the event, NSW Police warned punters that drug detection dogs will be out in full force, stating that they would deny entry to anyone found to have illicit substances on them.

They also said patrons would be refused entry if a dog detected the presence of prohibited drugs on them — even if no drugs were actually found in a search.

“Police will exclude any person from the venue that the drug dog indicates has or who has recently had drugs on them, regardless of whether drugs are located,” South West Metropolitan Region commander Assistant Commissioner Peter Thurtell said.

“Quite simply, if you handle or use drugs you will not be permitted to remain at the venue.”

It’s understood that this is the third time NSW Police have used this strategy at a Sydney music festival, after State of Trance in April and Midnight Mafia in May.

At Midnight Mafia, one woman was allegedly found in possession of almost 1600 MDMA capsules.

However, numerous festival-goers took to social media shortly after to say they were denied entry to the event after they were searched by police on their way in, despite having nothing incriminating on them.

Prominent Sydney criminal lawyer Greg Goold told ABC it was unclear what power police were using to deny entry, and it could be a breach of civil liberties.

“There’s nothing in the Act which would provide a power for the police department to refuse a person access to a concert because they’ve raised suspicion of drug detection,” he said.

“That (dog indication) could have been caused by someone having a joint in their vicinity and the smell catching in their clothing.

“Basically it’s coming down to guilt by association.”

Sniff Off said only 45 out of 187 people were found with drugs at Midnight Mafia, meaning that in 76 per cent of searches, no drugs were found.

Among those arrested were a 21-year-old woman allegedly found in possession of almost 1600 MDMA capsules and an amount of cocaine; another 21-year-old woman allegedly carrying nearly 550 pills; and a 19-year-old woman allegedly caught with 200 capsules.