British health authorities repeated a warning to drug users on Monday that a batch of heroin contaminated with anthrax was probably circulating in Europe, posing a potentially serious health threat.

British health authorities have issued a warning after a second case of anthrax has been found in an injecting drug user in London, making a cause of concern, as it is likely that a batch of heroin contaminated with anthrax is probably circulating in Europe, posing a potentially serious health threat.

The Health Protection Agency and NHS London have confirmed that the latest case was being "treated in a London hospital".

Issuing a statement, the agency said, "This is the third case of anthrax seen in an injecting drug user in England since similar cases were first seen in Scotland in December 2009".

"Twenty-four cases have so far been confirmed in Scotland and one in Germany. Similarities to the cases in Scotland suggest that the heroin, or a contaminated cutting agent mixed with the heroin, is the likely source of infection".

Professor Lindsey Davies, Regional Director of Public Health from NHS London, threw a word of caution, saying, "I urge all heroin users in London to be extremely alert to the risks and to seek urgent medical advice if they experience signs of infection such as redness or swelling at or near an injection site or other symptoms of general illness".

A deadly bacterial infection, Anthrax mostly occurs mostly in animals in Asia and Africa.