Sweetened fruit drinks are often marketed as a healthier alternative to non-diet soft drinks but are just as likely to cause weight gain and increase the risk of diabetes, researchers said on Monday.

"The public should be made aware that these drinks are not a healthy alternative to soft drinks with regard to risk of type 2 diabetes," Julie Palmer and colleagues at Boston University wrote in their report, published in the Archives of Internal Medicine.

Type 2 diabetes, the most common form of the disease, is closely linked to obesity and has become more common worldwide.