Two suspected cases of botulism have been discovered by NHS Greater Glasgow and Clyde.

Both are in a serious condition and are receiving treatment in Glasgow.

The source of these infections is contaminated heroin.

Botulism is a potentially fatal illness which can cause paralysis of the arms, legs and the muscles that control breathing.

One of the patients is from the Greater Glasgow and Clyde area while one is from the Lanarkshire area.

This takes the total number of cases currently in Glasgow hospitals to four.

Five cases were reported earlier this month. One patient was discharged after treatment but a woman in Ayrshire died.

Four patients remain in Glasgow hospitals, three from the Glasgow area and one from Lanarkshire.

NHS Greater Glasgow and Clyde, NHS Lanarkshire, Police Scotland and Health Protection Scotland are investigating.

Dr Catriona Milocević, NHS Greater Glasgow Consultant in Public Heath Medicine, said: "I urge all drug injecting heroin users to be extremely alert and to seek urgent medical attention from Accident and Emergency if they experience any early symptoms such as blurred or double vision, difficulty in swallowing and speaking and/or inflammation at the injection site.

"It is important for injecting drug users to engage with the wide range of services we offer designed to help them tackle their addictions. However for those who continue to inject it is extremely important that they seek urgent medical help if they show these early symptoms.

"Heroin users should avoid injecting heroin into their muscles. Injecting heroin into a vein or smoking can reduce the risk of botulism, although not using heroin at all is by far the best course of action."

A spokesman for Police Scotland added: "enquiries are continuing".