AS investigations continue into the possibility that anthrax bacteria is killing needle-using heroin addicts in Strathclyde, a new fatality last night brought the death toll to 11.

The man lost his fight against massive infection and organ failure in Glasgow's Stobhill Hospital. There are still 15 people seriously ill in hospital with the condition.

His death comes as public health officials stated they were considering anthrax poisoning as part of their investigations.

However, if anthrax is found to be the cause, the situation should not cause unnecessary alarm amongst the general population, a leading expert on infection has said.

Professor Hugh Pennington, of Aberdeen University, believes the deadly bacteria, known best as a potential biological warfare agent, is unlikely to spread into non-drug injecting communities.

Professor Pennington said anthrax was a naturally occurring bacterium found in animals such as horses, pigs, camels, sheep and goats - but was highly lethal to humans.

The scientist added: ''Traditionally, anthrax is an occupational disease acquired from handling infected hides which then enters the body through skin lesions.''

It is thought that quantities of heroin smuggled from the Middle East may have been contaminated with the deadly bacteria.