SAN FRANCISCO – UnumProvident Corp., the nation’s largest disability insurer, systematically sought ways to avoid paying claims to millions of California customers, a lawsuit claims.

The lawsuit filed Friday in Superior Court by policyholders seeks class-action status. It comes less than a month after the company was ordered to pay an $8 million fine to settle similar charges against the company by state insurance regulators.

The lawsuit seeks billions of dollars in premium refunds and damages for denied claims. The suit also names UnumProvident subsidiary Paul Revere Life Insurance Co.

The lead plaintiff in the case is former Berkeley chiropractor Joan Hangarter, who won a unanimous $7.7 million federal jury award after she became disabled by tendinitis and Paul Revere denied her benefits.