Illegal drug-laced ‘sweets’ are readily available for sale in local high street shops and markets, a headteacher has warned, after two students fell ill.

Tim Fox, headteacher of Highbury Fields School in Highbury Hill, warned parents of the dangers of “incredibly dangerous” synthetic cannabinoids not to be mistaken for ordinary sweets.

In a letter sent on October 15, Mr Fox wrote that the sweets contained “mind-altering” chemicals.

A presentation shown to parents and pupils displayed images of packaged sweets that appeared to have familiar branding but indicated contamination.

Brands such as Nerds were instead labelled “Medicated Nerds”.

In May, three children aged 12 and13, were taken to a hospital in Epsom after eating sweets they believed to contain naturally-occurring cannabis, according to The Guardian.

The chemicals are “similar to chemicals found in the marijuana plant” but are entirely synthetic, according to the National Institute for Drug Abuse.

They may cause symptoms such as extreme anxiety, confusion, hallucinations, vomiting, rapid heart rate and suicidal thoughts.

Highbury Fields School, which has more than 800 students, has been approached for comment.