(Bloomberg) — MetLife Inc. said it will sue to overturn a U.S. finding that subjects the insurer to tighter oversight under the Dodd-Frank law, becoming the first non-bank financial firm to file such a challenge.

A complaint will be filed today in federal court in Washington to oppose the U.S. Financial Stability Oversight Council's designation of the insurer as a systemically important financial institution, the company said in a statement. The largest U.S. life insurer called the label premature, and said it has offered "substantial and compelling evidence" it isn't a SIFI.

MetLife "has operated under a stringent state regulatory system for decades," Chief Executive Officer Steve Kandarian said in the statement. "Adding a new federal standard for just the largest life insurers and retaining a different standard for everyone else will drive up the cost of financial protection for consumers without making the financial system any safer."