A terrifying new strain of the drug Spice has been described as turning people into "the walking dead".

The dangerous effects of the drug have been exposed in recent documentaries which showed prisoners high on Spice.

It has even been highlighted in a storyline in popular soap Emmerdale, where prisoner Aaron Dingle took Spice after being bullied and abused by fellow inmates.

And last week, shocking footage taken on the streets of Manchester showed Spice users 'freezing' and even collapsing after taking a new strain of the drug.

There are now concerns the new drug could spread across the country.

But what is Spice and why is it so dangerous?

Spice is a mix of herbs and man made chemicals with mind-altering effects.

It is often called ‘synthetic marijuana’ or ‘fake weed’ because some of the chemicals in it are similar to ones in marijuana but its effects are sometimes very different from marijuana, and frequently much stronger.

The substance, which like marijuana is smoked in cigarette papers, is made from dried plant material and chopped up herbs in a mixture of colours.

The active ingredients are sprayed onto the plant material. The ‘legal high’ first emerged in the UK in 2004.

At first, people believed Spice was simply a mixture of harmless herbs that had a similar effect to marijuana, so it was legally sold all over the world, especially via the internet.

It was attractively packaged in small colourful sachets, and generally marketed as a herbal smoking tobacco substitute, or as incense.

Spice can be sold as potpourri, room fragrance or incense, purporting to be an innocent product for scenting rooms and will usually have the warning, ‘not for human consumption’ on the packet.

Is Spice illegal?

Last year the drug, along with similar substances, was reclassified as a Class B drug, giving ‘new psychoactive substances’ the same status as cannabis.

How does it affect people?

While some users may end up feeling happy and giggly, others can experience psychotic episodes, violent outbursts, extreme paranoia and breathing difficulties.

Because Spice is still relatively new - it has been sold online for about ten years - and because those who manufacture the drugs often change the chemical makeup, the long term effects aren't yet known.

In 2015, legal highs were linked to more than 100 deaths in the UK.

How is the new strain of Spice different?

The concerns are the new strain of Spice is making people 'freeze' - leading to them being dubbed the walking dead. Some even keel over completely.

"People are falling without even putting out their hands, which would be your natural instinct," a drug support worker in Manchester said. "They're just falling face down, injuring their face or the back of their head. It's horrible. It was bad enough before but this is another level."