Experts have voiced concern about the dramatic increase in the number of users of nicotine products such as chewing gum and patches after restrictions on their sale ended in 2001.

After kiosks and convenience stores started to stock the nicotine products, the number of users tripled and sales shot up by 111 percent, reports public broadcaster DR.

According to Henrik Rindom, a drug abuse expert at Hvidovre Hospital, the trend is worrying as it means many former smokers are maintaining a serious dependency.

“The fact that nicotine gum is handed out over the counter without a thought is unfortunate for users because they don’t receive help for their actual problem, which is how to end their dependency and how to work with their dependency,” Rindom told DR.

Anti-cancer charity Kræftens Bekæmpelse said it was also worried by the high use of products that are designed to help people stop smoking.

“I think it is deeply concerning that we know that people use these products for many years even though we don’t know what about their long-term effects,” spokesperson Inge Haunstrup Clemmesen told DR.

Following the criticism, the government health agency, Sundhedsstyrelsen, has promised to respond.

“We know it would be a scandal if we didn’t listen to clever experts in their field,” Sundhedsstyrelsen spokesperson Jens Heisterberg told DR. “And when they express concern about the free sale of nicotine products, then that’s something we need to listen to.”

Concerns are also mounting about the rising use of electronic cigarettes that administer nicotine through water vapour rather than smoke.

According to Sundhedsstyrelsen figures from 2012, three percent of the Danish population over age 15 use electronic cigarettes, around 150,000 people, a third of whom smoke electronic cigarettes daily.

The sale of the liquid nicotine used in electronic cigarettes is not currently permitted in Denmark but is easily available online from other EU countries where it is legally available, or through illegal Danish distributors.

The blossoming black market has led Dansk Folkeparti to propose legalising the sale of liquid nicotine so that consumers can make sure they buy a high quality product.

“Currently a lot of people are making their own fluids for the electronic cigarettes and that can lead to harm as people don’t know what they’re doing,” DF's health spokesperson, Liselott Blixt, told Berlingske. “That’s why it would be safer to legalise liquid nicotine in order to avoid some of the damage that we have seen.”

In May, Sundhedsstyrelsen reported that Danes were being poisoned after handling liquid nicotine, which is highly toxic even in small doses.

Despite these risks, DF argues that electronic cigarettes do not pose as much risk to the public as ordinary cigarettes.

“That was the purpose of the first smoking law, to prevent passive smoking," Blixt said. "That was largely successful but the last stretch of the road is to legalise nicotine products that don’t harm others.”