Image copyright Getty Images Image caption The drug is made to look like normal cannabis

A string of recent deaths in New Zealand is being attributed to the rise of so-called synthetic cannabis.

A man in his 20s died on Tuesday night, bringing the number of fatalities this month linked to the illegal substance to eight.

The drug consists of dried plants sprayed with synthetic drugs - it triggers effects similar to cannabis but is more powerful and dangerous.

Synthetic cannabis has already caused huge concerns in the US and Europe.

In each of the eight deaths this month, the victim was thought to have used the drug before dying or was found with the drug on them.

The actual substance in the drug responsible for the deaths is not yet known.

All eight deaths have occurred in Auckland and authorities say there is a much higher number of non-fatal cases where people had to be taken to hospital.

Image copyright Getty Images Image caption Synthetic cannabis was briefly legal in New Zealand in 2014

Earlier this month, the Auckland City District Police issued a warning on Facebook over the drug use and the apparent link to the rising number of victims.

"This is not an issue unique to Auckland," the statement warned. "Police are also concerned at the impact of synthetic cannabis in other communities in New Zealand."

Auckland police also took the rare step of releasing CCTV footage of a man violently ill and barely able to stand after smoking synthetic cannabis.

"We have grave concerns as users don't know what poisonous chemicals they are potentially putting into their bodies when they're smoking this drug," Det Insp Lendrum said.

What is synthetic cannabis?

Actual cannabis contains an active ingredient which interacts with certain receptors in the brain.

Synthetic cannabis is dried plant matter sprayed with chemicals that interact with the same receptors.

Produced and sold illegally, the chemicals used vary a lot. That means the effect of the drug is a lot less predictable, so a lot more dangerous.

Effects can be extreme, including increased heart rates, seizures, psychosis, kidney failure and strokes.

Cannabis-simulating substances - or synthetic cannabinoids - were developed more than 20 years ago in the US for testing on animals as part of a brain research programme.

But in the last decade or so they've become widely available to the public.

Synthetic cannabis was briefly legal in New Zealand but was banned in 2014.

Image copyright AFP Image caption In the UK, the drug was widely sold under the name Spice

In the UK, synthetic cannabis was also temporarily legal, being sold under a variety of names most prominently Spice and Black Mamba.

The drugs were banned in 2016 but continue to cause widespread problems in the country.

Synthetic cannabis has also been banned in the US but continues to be widely available as an illegal drug.

For help and support on drug use, visit the BBC Advice pages or in the UK, speak to drug advice service Frank.

If you're in New Zealand, you can find help at the Ministry of Health's support pages.