An American senator is asking the U.S. government to prevent the sale of so-called "electronic cigarettes" until more is known about them.

The devices resemble a real cigarette, but consist of a stainless steel tube with a chamber that holds liquid nicotine. The E-cigarettes have been marketed as a healthier alternative to tobacco, and since they do not need to be lit, some people are using them to evade smoking bans in public places.

The E-cigarette is powered by a rechargeable battery and produces a heated mist of nicotine that the smoker inhales.

New Jersey Sen. Frank R. Lautenberg sent the Food and Drug Administration a letter Monday saying that the agency should ensure E-cigarettes are not sold until they've been studied more.

An FDA spokeswoman says the agency will respond directly to the senator regarding his concerns.

Electronic cigarettes were first developed in China in 2004, and are now sold there as well as in Brazil, Canada, Finland, Israel, Lebanon, the Netherlands, Sweden, Turkey and the United Kingdom.

E-cigarettes have not undergone rigorous clinical trials in any country, although some distributors have done their own testing.

With files from the Associated Press