A MAN was last night in a critical condition following his collapse in a city centre park after he is believed to have taken a so-called "legal high".

A major police probe is underway following the discovery of the man in his early 30's, who keeled over in a busy Southampton park before passing out unconscious.

Last night Hampshire police said they were unable confirm full details of the incident as their investigations were still waiting for results from the hospital.

But witnesses told the Daily Echo the man, in Palmerston Park, had taken a legal high named "spice".

The synthetic cannabis has worrying side effects such as vomiting, seizures, psychosis and, in some cases, death.

Following the man’s collapse yesterday, concerned bystanders rushed over to help him, describing him as unresponsive and "turning blue".

Paramedics were called just after 12.30pm and took the seriously ill man to hospital for emergency treatment.

Police deployed several cars and one police van, before erecting a cordon, sealing off a 20 ft area where he had collapsed.

One man, who did not want to be named, said: “Spice has struck in a bad way. He just collapsed and went blue. There was no response. I heard he’s critically ill. It’s a bad drug and some people can have reactions.”

Another witnesses added: “Anyone can buy this drug, it’s crazy. You see the empty packets all over the park.

“It’s sold in shops in Southampton. You can be 16 and buy it while you have to be 18 to buy a bottle of vodka.”

A Hampshire Constabulary spokesman confirmed they were called after a man was found collapsed and unresponsive in Palmerston Park.

The added: “At the current time, the cause of his collapse is unclear and officers are trying to establish the circumstances."

“He has been taken to Southampton General hospital for treatment.

“A small area of Palmerston Park has been cordoned off around the main thoroughfare but the park is still completely accessible to pedestrians.”

It comes after the Daily Echo launched its Say No To Legal Highs campaign, following a spate of deaths and people becoming seriously ill after taking so-called "legal highs".

Schoolboy Adam Hunt, from Millbrook, died in hospital in August 2013 – five days after falling seriously ill after taking AMT and etizolam.

Trainee doctor Doug Ferguson, 19, from Chandler’s Ford, died after taking AMT in June 2012 and married father William Nutter, 32, from Andover, died after consuming AMT the following month. And in April, bereaved mum Vivian Ryan called for the banning of legal highs which she believes killed her son Clint Broomfield, of Radstock Road in Woolston.

The Government has announced it intends to ban legal highs.

What is Spice?

Synthetic cannabis known as ‘spice’ copies the effect of cannabis but can cause serious side effects such as vomiting, fits, psychosis and death.

It's been responsible for a string of hospitalisations across England and Wales.

These drugs are typically developed as liquids in the lab and then sprayed onto plant material and sold in foil bags or added as a powder to cigarettes.

They contain strong chemicals, many of which are unregulated in the UK.

Since 2009 a number of formulations have been banned. But suppliers, mainly in China, simply tweak the ingredients to get round the law.