Britain is facing a flood of illegal cigarettes that pose potentially fatal health risks, the government said on Wednesday as it launched a campaign to deter smokers from buying cheap contraband tobacco.

Customs minister John Healey said more than half the illegal cigarettes currently being seized were counterfeit, as smugglers had started manufacturing their own versions of popular brands in factories in Eastern Europe and China.

The replicas, made without legal safeguards, tend to be even worse for people’s health than normal cigarettes. Research has shown them to contain substantial contamination by heavy metals, including carcinogens like cadmium and arsenic.

“If you smoke a packet of 20 fake cigarettes every day, it’s like smoking 100 normal ones,” Healey said.

“What you’re doing is not only funding organised crime, it can also be even more dangerous for your health than real cigarettes.”

The minister said consumers seemed unaware of the dangers despite illegal cigarettes estimated to account for 15 percent of the total number smoked in Britain, costing the exchequer some 2.0 billion pounds in lost revenue from duty.

“The black market is big business,” he said. “Customs are regularly seizing 5 to 6 million cigarettes in a container. That could keep a small town in fags for well over a week.”

While high duties have long made smuggling a problem, better law enforcement and relaxation of limits governing how many cigarettes travellers can bring back from the European Union has led criminals to protect their margins by making their own.

According to government research, counterfeit cigarettes being sold in the UK contain five times as much cadmium, which can severely damage the lungs and is linked with kidney disease.

They also have nearly six times as much lead and high levels of arsenic - which increases the risks of lung, liver and other cancers.

Healey said Customs had been working with the big tobacco companies who themselves are losing money to the counterfeiters.

They have discussed the possibility of introducing “covert markings” which would make the detection of fake cigarettes easier but could raise costs for manufacturers.