Norfolk police suspect the deaths of four men and two women over the past nine days could be linked by their use of a "particularly pure" batch of heroin.

It is the second time in recent weeks that police have warned about the dangers of China white.

Nine people are thought to have died over the past two months in Bristol after taking the drug.

Earlier this month police in Sheffield issued a similar warning after a 24-year-old man died of an overdose.

'Stronger than normal'

Norfolk police's drugs education officer, PC Richad Price, said users may be taking China white not realising it was far stronger than ordinary street heroin.

He said: "We are almost certain that all six deaths are drug-related and we are reasonably happy that they all relate to this particular brand.

"Users need to be aware that they may be taking something considerably higher in purity and therefore of greater danger. The outcome of its use cannot be predicted."

The victims lived in Norwich and Great Yarmouth and the latest died on Thursday night.

Most heroin used on the streets is light or dark brown powder, hence its nickname "brown sugar".

But China white resembles pharmaceutical heroin used in hospitals. As its name suggests, it is a white powder.

PC Price said they were trying to trace the source of the batch and he said they would be liaising with colleagues in Bristol.