Indoor tanning heightens the risks of developing non-melanoma skin cancer, particularly in those under the age of 25 using sunbeds, according to new research.

The researchers, at the University of California San Francisco, believe indoor tanning may account for over 170,000 cases of non-melanoma skin cancer in the US alone.

While these cancers, such a basal cell carcinoma, are not as deadly as melanoma, they affect huge numbers of people worldwide.

The US researchers looked at the results of 12 studies involving 9,328 cases of non-melanoma skin cancer.

Ever using indoor tanning was associated with a 67% higher risk of developing squamous cell carcinoma and a 29% higher risk of developing basal cell carcinoma, compared with never using a sunbed.

The researchers calculated that the effect of ultraviolet light use in indoor tanning could account for 3.7% of cases of basal cell carcinoma and 8.2% of cases of squamous cell carcinoma.

If you are under 25 and expose yourself to sunbed tanning, you have an a significantly increased risk for basal cell carcinoma 

"This suggests a critical period for exposure during early life and a potential dose-response effect," the researchers said.

The study is published on bmj.com.