The A.M. Best Company has upgraded the financial strength ratings of the property and casualty companies of Worcester’s The Hanover Insurance Group to "A" from "A-."

In a statement, Best cited the company’s "excellent risk-adjusted capitalization, stemming from improved operating earnings," "improved underwriting performance and favorable reserve development," as well as "improved financial leverage and financial flexibility since 2003." A.M. Best also recognized the benefits from the sale of The Hanover’s life insurance business.

Best’s action represents the third time The Hanover’s financial strength ratings have been upgraded over the past 15 months. Two of the industry’s other leading, independent analysts, Moody’s Investors Service and Standard & Poor’s, upgraded the company’s ratings last year.

The financial strength upgrades apply to The Hanover Insurance Company, Citizens Insurance Company of America, the companies of the AIX Group, and all of their subsidiary companies.