A group of schoolchildren fell ill after taking fake Xanax tablets which may have been laced with Fentanyl, it has emerged.

A number of pupils from Sussex bought the pills – advertised as the anti-anxiety drug – “very cheaply”.

They were taken to hospital and with symptoms linked to the potentially deadly synthetic opioid, according to East Sussex County Council.

One person has been arrested on suspicion of supplying the drugs.

According to the local council, “the symptoms exhibited by the young people indicate the tablets also contained Fentanyl.”

Robertsbridge Community College said “a small number” of its pupils had taken the pills.

Head teacher Zak Vice said: “This is clearly a very serious matter and the college has acted swiftly and robustly.

“Our students are very aware that misuse of drugs is not only extremely dangerous, but completely unacceptable.

“We are working with police, NHS and East Sussex County Council to provide appropriate medical support to the pupils involved.”

Secondary schools in Ringmer, Chailey and Lewes also confirmed they were warning parents about the dangers of taking the drug.

Parents are being warned potential effects could include dizziness, fainting, hearing loss, loss of consciousness, coma and even death.

Insp Jonny Hartley, of Sussex Police, said: “We will do everything we can to keep juveniles out of the criminal justice system, but our stance on the supply of this will be robust.”

He said the force was working with the local authority, and schools have been asked to warn pupils of the dangers of taking the drug.

What is Xanax?

Xanax, also known as alprazolam, is a powerful tranquiliser, widely used in the US to treat anxiety and insomnia.

A class C drug, It is not available through the NHS, and is only available via private prescription in the UK.

But it is thought dealers have flooded the British Isles with fake Xanax, prompting a series of warnings from various agencies.

More than 200 deaths have been linked to the misuse of versions of the drug in the UK since 2015.

Counterfeit Xanax bars with a street value of more than £1m have been seized at UK ports and airports since 2016.

Last year, the BBC found that children as young as 11 were being treated by ambulance services after taking fake versions of the drug.

Fentanyl is a painkiller 100 times more potent than morphine and has been linked to more than 125 deaths in the UK.

It is a man-made drug which mimics the effects of natural opioids such as heroin.