CHICAGO (Reuters) Jan 2000- Some forms of chlamydia, like other sexually transmitted diseases, will increase a woman's risk of developing cervical cancer, Finnish researchers say.

A study of women in Finland, Norway and Sweden found a strong link between three of the 10 serotypes of chlamydia and cervical squamous cell carcinoma (SCC), an increasingly common cancer.

The study examined samples provided to serum banks by 530,000 women, then focused on 128 of them who were each matched against three controls.

It found women with chlamydia serotype G had more than six times the risk of developing cervical cancer. Those with serotype I had four times the risk while those with serotype D had nearly three times the risk.

"Exposure to more than one serotype increased the risk for cervical SCC,'' wrote study authors Tarja Anttila of the National Public Health Institute, Oulu, Finland, and Jorma Paavonen, of the University of Helsinki, in this week's Journal of the American Medical Association.

Chlamydia is transmitted by a group of microorganisms of a size between bacteria and viruses, and can lead to various genital, eye and lymph node infections. Like a virus, it can only multiply after invading the body's cells.

Among sexually transmitted infections, human papillomaviruses, or genital warts, are the leading cause of abnormal cell growth in the area around the cervix. Damage caused by the diseases can lead to cell mutation and cancer.