Watton Medical Practise alerted locals in an announcement earlier today.

The centre says there is an increased risk of overdosing as a result.

A spokesman for the centre said: "We have received reports that heroin in the Norwich area may be contaminated with highly dangerous synthetic opioids, including fentanyl.

"These substances are extremely potent. Even a very small amount can cause severe breathing, unconcioussness and death.

"While the safest option is to not use non-prescribed drugs, if you do, go low and slow, do not use alone, avoid mixing drugs and look after one another.

"Know the signs of overdose: slow to no breathing, unconsciousness, snoring or rasping sounds and blue lips or fingertips.

"Call an ambulance immediately and use testing services where available."

A similar warning by the health service was issued in December by the drugs charity, Change, Grow, Live.

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