Britain will start regulating electronic cigarettes and other products containing nicotine as medicines, according to the country's top regulator.

In a statement on Wednesday, the Medicines and Health Regulatory Agency said it would treat e-cigarettes as medicines "so that people using these products have the confidence they are safe, are of the right quality and work." E-cigarettes are battery-operated products that turn nicotine into a vapor that is inhaled by the user.

Britain's chief medical officer Sally Davies said it was best for smokers to quit but it was appropriate e-cigarettes should be properly regulated. Cigarettes are exempt from the regulation.

In the U.S., the Food and Drug Administration regulates e-cigarettes used for therapeutic purposes and says it plans to assert regulatory authority of the products in the near future.