A £9M Derby trade in counterfeit cigarettes made with toxic ingredients including asbestos, rat droppings and dead flies, has left at least half a dozen smokers ill.

Trading standards officers fear the number of people laid low could be much higher, but incidents haven't been reported because people didn't realise the cigarettes were responsible.

In one case, a 15-year-old boy who bought fake cigarettes was "violently ill".

Officers warn the trade poses a "significant threat to public safety".

The officers spoke out after the sentencing of a shopkeeper and his assistant caught with £20,000 worth of counterfeit and smuggled cigarettes.

Sirwan Omer Hussein and Sarwen Saeed Yousuf admitted storing thousands of illicit cigarettes inside two secret hiding places at Derby Mini Market in Lower Dale Road, Normanton. The shop has since been sold and is now under different ownership.

Following the hearing, a trading standards enforcement officer told the Derby Telegraph that some fake cigarettes contained "high traces of poisonous compounds" and had been smuggled in from countries such as Russia, China and Pakistan.

Cigarettes recently intercepted by the UK Border Agency contained asbestos, rat droppings, human faeces, dead flies, mould, and insect eggs.

Studies have shown that when compared to legal cigarettes, fake smokes can contain five times the level of cadmium, six times as much lead, 160% more tar and 133% more carbon monoxide.

The Derby trading standards officer said: "They will put anything in as long as it looks like tobacco and makes them feel heavier.

"In Derby, we've had people phone in about illicit tobacco products that have caused them to be off work for two or three days.

"Sometimes the effects are long-term. For instance, if they contain asbestos the customer may not experience the effects for a number of years.

"If people buying cheap cigarettes knew what they might contain, they may think twice about buying them."

As taxes increase on genuine cigarettes, the illegal market continues to grow.

The profit margin to Derby shopkeepers is thought to be up to 50% of the selling price.

The Derby officer, who did not want to be named, said there is also strong evidence to suggest the trade, worth £9m a year in Derby, helps finance organised crime and even terrorism.

In the case of Hussein and Yousuf, Southern Derbyshire Magistrates' Court heard 1,334 packs of 20 counterfeit cigarettes were discovered.

A further haul of 18,800 counterfeit cigarettes was seized from a building in Harrington Street.

Hussein, 32, of Clarence Street, and Yousuf, 30, of Violet Street, were given community orders after admitting possession of counterfeit tobacco products.

Joanne Groom, prosecuting on behalf of Derby City Council, said the pair's actions meant local legitimate traders had been "unable to compete" with the store, which was selling the fake cigarettes for £3.50 per packet.

However Andy Cash, in mitigation for both defendants, said the pair felt they needed to sell the counterfeited cigarettes in order to kept the business afloat.

He said: "What seems to have happened is all the shops in the area were doing it. In order to compete, they felt they had to become part of what was going on."

Mr Cash added that although they realised they were doing wrong, they did not realise it was a matter for a criminal court.

Hussein was given a 12-month community order and told to carry out 120 hours of unpaid work and pay £200 towards court costs.

Yousuf was also handed a 12-month community order and told to carry out 80 hours of unpaid work. He was ordered to pay £100 costs.