WASHINGTON (Reuters) - A top Democratic senator is seeking information on Cigna Corp's treatment of small businesses as part of an ongoing investigation into the health insurance industry, the lawmaker said on Wednesday.

Senate Commerce, Science and Transportation Committee Chairman John Rockefeller, in a letter to the company, asked for information about its handling of the small business group health insurance market and whether it dropped those whose employees made numerous and costly benefit claims.

Although the insurer "recently denied that Cigna 'purges' small business group health accounts, the committee has reviewed information suggesting otherwise," Rockefeller wrote to Cigna.

The senator asked Cigna to explain its February 5 comments to investors about its approach to small businesses, in which company executives used terms such as "purge" to describe their strategy. Rockefeller requested answers by August 19.

He also asked the company how much money it had saved in medical claims as a result.

Representatives for Cigna could not be immediately reached for comment.

A copy of the letter was posted on Senate committee's website at http://commerce.senate.gov/public/_files/80509HanwayLetter.pdf