The statistics are revealed by increasingly worried frontline workers who are warning drug users to be extra vigilant.

Amanda Scott, needle exchange/drug worker for Cornerstone in Leven, said: "There are going to be deaths in this area because of this.

Many people here have big, big habits and are dependent on what's available.

"This heroin obviously came into our area for the first time a week past Friday and it's everywhere."

According to Fife Constabulary, supplies of heroin to the area are so low, unscrupulous suppliers are contaminating the drug with other ingredients, producing a distinctive red-coloured heroin.

Users are presenting symptoms which include unconsciousness immediately after injecting and associated wounds, such as cuts to the head.

People are also sedated for hours at a time and turn up at Cornerstone with memory loss, extreme vein damage and potentially fatal signs of deep vein thrombosis (DVT)

"They are incoherent, with blurry vision, poor motor skills and muscle movement," said Amanda.

"Everyone in our waiting room yesterday was sitting with one eye shut! We've never seen this before."

She explained: "This heroin is being mixed with anti-psychotic drugs such as seroquel and amitriptyline and it crystallises in the barrel of the syringe and in the veins.

"People think that if they inject it quickly enough they will be all right. Others are saying it turns "plasticky" when smoked. It's worrying."

NHS Fife commented the heroin was similar to batches first reported in Ayrshire, where they were linked to fatal and non-fatal overdoses.

A spokesperson said: "The prepared solution rapidly crystallises in the syringe, and users injecting quickly risk causing blockages leading to vein damage including abscesses or thrombosis.

"Once injected, deep levels of unconsciousness have been reported, along with significant memory loss."

Det Insp Neil Kerr of Fife Constabulary said he was particularly concerned for 'some-time' users who were not aware of the drug's potential risks until too late.

He added: "People using heroin every day will see the actual visual difference, although that may not be at the forefront of their minds.

"Those that are involved in supplying it will be bulking it out so people should be very aware of what they are sticking in their veins."

According to figures just released by the General Register For Scotland, there were 28 drug related deaths in Fife last year - that compares with just three fatalities in 1996.

Fife Constabulary would welcome people with information to come forward on 01592 251111.