CCTV footage has been released showing legal high users fighting, falling over and collapsing unconscious in a busy high street in Newcastle. Northumbria Police published the montage to raise awareness of the dangers posed by new psychoactive substances (NPS) being sold both in shops and online.

In 2012, Newcastle reported the highest proportion (35%) of people accessing drug treatment services for legal high-related problems compared to anywhere else in the country.

Simon Swallow, of the North East Ambulance Service, said: "These so-called legal highs are not safe to use, carry a serious health risk and are putting people's lives at risk.

"We raised our operational status to 'Severe Pressure' in December as result of growing demand on the service during winter and these call-outs are putting an additional burden on our service by preventing us from being available to attend other life-threatening emergencies such as heart attacks and strokes.

"We are urging people not to take these so-called legal highs as they are putting their own lives in danger and also endangering the lives of others, because these calls are potentially delaying our response to someone else who is suffering a heart attack or other life-threatening condition."

A joint task force created in Northumbria in January to combat the problem has seen the number of police calls relating to legal highs drop by more than half, with ambulance call-outs cut by two thirds. In February, the North East Ambulance Service received 97 calls involving legal highs compared to the 263 they got in January. The police received 85 calls compared to the 176 in January.

Work by the task force includes undercover police test purchases, executing search warrants and issuing warnings to businesses thought to be selling psychoactive substances.

Vera Baird, Northumbria police and crime commissioner, said: "I have been a determined campaigner on this issue, calling for the government to take firm action against those who make these products and those who sell them. Firm action is certainly being taken here in Newcastle and through excellent partnership working we have the results to prove it.

"Local residents can rest assured this is a top priority for me and I will ensure our officers do everything within their power to get those selling these substances before the courts so we can prevent people from getting addicted to them and putting their lives at risk. We cannot, nor should we, tolerate the sale of legal highs on the streets of Newcastle."