While sun exposure has long been linked to skin cancer, a new Swedish study shows it also dramatically reduces the risk of suffering blood clots, one of the authors of the report said on Wednesday.

"We found that women who suntan had about 30 percent lower risk of suffering blood clots," said Pelle Lindqvist, an associate professor at the obstetrics and gynecology department at the Karolinska University Hospital in Stockholm.

"There is also a 50-percent higher risk of blood clots in December, January and February in Sweden, when there is the least sun here," he told AFP.

Lindqvist and two colleagues at Lund University in southern Sweden studied the sunning habits of 40,000 Swedish women surveyed in 1990 about their habits, including whether they suntanned in the summer, the winter, used a sun bed or travelled south to catch the golden rays.

The researchers then followed the women's medical development for the next 12 years, and found that 312 had developed thrombosis, or blood clots.

Even adjusted for factors like exercise, smoking and alcohol habits and weight, the research showed that any amount of suntanning helped lower the risk of blood clots.

The study, which was published in the March edition of the Journal of Thrombosis and Haemostasis, only looked at women, but Lindqvist said he suspected men drew similar benefits from sunning.

"By sunning, you avoid a shortage of Vitamin D in the winter when people here in Sweden very often suffer a deficiency of that vitamin. It is only during the summer that we really have enough Vitamin D," he said.

It remained unclear why Vitamin D was important for the prevention of blood clots, Lindqvist said, adding that and other questions raised by the research would be the focus of future studies.

As for balancing the benefits of sun exposure against the risks of contracting skin cancer, he stressed that people should always avoid sunburn.

"But you should go out a bit every day, and it's not true that it's enough to go out late in the afternoon. You really should go out in the middle of the day, because that is when the production of Vitamin D occurs," he said.

A US study published early last year also showed that moderate sun exposure and the related production of Vitamin D improved survival rates for cancer victims, suggesting the benefits of sunning outweighed the skin cancer risks, especially in northern latitudes.

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AFP 251547 GMT 03 09