The U.S. Food and Drug Administration said on Thursday it will review wireless phone safety following a recently published study that raised concerns about a heightened risk of brain cancer.

Swedish researchers said last month the use of cellular phones over a long period of time can raise the risk of brain tumors.

Their findings contradict a number of earlier studies and are "difficult to interpret," the FDA said in comments posted on its Web site.

Still, the agency said it "plans to convene a meeting in the near future to evaluate research conducted to date in this area and identify gaps in knowledge that warrant additional research."

It also will continue to monitor studies for possible health problems stemming from exposure to radio frequency energy.

The researchers at the Swedish National Institute for Working Life compared data from 2,200 cancer patients and an equal number of healthy patients.

Those who heavily used wireless phones had a 240 percent increased risk of a cancerous tumor on the side of the head where they used their phone, they reported.

Their results, published in the International Archives of Occupational and Environmental Health, defined heavy use of wireless phones as 2,000 or more hours, or about one hour per day for 10 years.