(Reuters) - The U.S. Food and Drug Administration is strengthening its regulation of tanning beds, which have been shown to increase the risk of skin cancer.

The FDA, which is reclassifying sun lamp products from low risk to moderate risk, said on Thursday that in future sun lamp manufacturers must seek approval before they market a new product.

In addition, tanning beds must carry a visible warning against their use in people under the age of 18. Warnings about the risk of skin cancer must be included in any user instructions, brochures or marketing materials on the internet.

The requirement that beds carry a label warning against use in young people does not carry any legal weight and salon owners would not face fines if they allowed under 18-year-olds to use them.

Some dermatologists and public health advocates had argued for an actual restriction, which would have carried penalties for violators.

"We applaud the FDA for taking this important first step," said Dr. Brett Coldiron, president of the American Academy of Dermatology Association in a statement. "However, we recognize that there is still more work to be done to protect the public from these dangerous devices."

A study by the American Academy of Dermatology found that people exposed to ultraviolet radiation from indoor tanning faced a 59 percent higher risk of melanoma, a deadly form of skin cancer.

Dr. Jeffrey Shuren, director of the FDA's Center for Devices and Radiological Health, said repeated UV exposure from sun lamp products poses a risk of skin cancer for all users, "but the highest risk for skin cancer is in young persons under the age of 18 and people with a family history of skin cancer."

(Reporting by Vrinda Manocha in Bangalore; Editing by Kirti Pandey)