Health leaders have issued a warning about potentially dangerous batches of heroin which are believed to be circulating across the country. 

Public Health England says there are 'early signs' a number of overdoses may be caused by heroin mixed with a potent and dangerous synthetic opioid.

It comes after a sharp rise in the number of overdoses linked to people using drugs in several areas across England.

To date, there have been at least 46 poisonings resulting in 16 deaths but investigations are still ongoing. 

The areas affected include South London, the South East, South West and East of England.

Last month cahrity Open Road, which delivers services across Essex, Suffolk and Norfolk, issued the warning on its Facebook page. 

It said: "We have just received information from Essex Police that one of the county lines in Chelmsford may be mixing fentanyl into heroin batches.

"Please be cautious, look out for each other, and do not use heroin by yourself. Make sure you carry Naloxone.

"If you suspect someone is having an overdose please call 999 immediately and put the person in the recovery position."

Public Health England said it is working closely with the National Police Chiefs’ Council (NPCC) and National Crime Agency (NCA) to investigate these incidents and prevent further deaths.

Read more >> Dangerous batches of heroin laced with potent painkiller circulating in Essex

They said people who use drugs, in particular heroin, should be extra cautious about what they are using and how much they take.

Rosanna O’ Connor, Director of Drugs, Alcohol, Tobacco and Justice at PHE, said: "We are urging drug users to be extra careful following reports of a sharp rise in the number of overdoses potentially connected to heroin, tragically with some deaths. We are urgently investigating with the police and local partners.

"We strongly advise anyone using drugs not to use alone and to test a small amount first.

"People need to look out for each other and be alert to any signs of an opioid overdose, such as shallow breathing, loss of consciousness and blue lips or fingertips.

"If someone does overdose it’s vital to act fast, call for an ambulance immediately and if possible use the opioid antidote, naloxone, which can save lives.

"We strongly advise all drug users to get support from local drug services, as being in treatment greatly reduces the risks of harm and overdose."