WASHINGTON » U.S. regulators have labeled insurer MetLife as a potential threat to the financial system, a designation that brings stricter government oversight.

MetLife said Thursday that the Financial Stability Oversight Council has designated the company as "systemically important." As a result, MetLife must increase its cushion of capital against losses, limit its use of borrowed money and submit to inspections by examiners. MetLife will come under the supervision of the Federal Reserve. Its primary regulator now is New York state.

Regulators saw a need for closer oversight of big financial companies that aren’t banks after the near-collapse of insurer American International Group threatened to bring down the global system in September 2008 during the crisis. The idea is to prevent a catastrophic collapse that could lead to another financial meltdown.

New York-based MetLife is the largest U.S. life insurer, with about $475 billion in assets under management.

In a statement, MetLife said it is "disappointed" in the decision and has given the regulators evidence showing it is not systemically important as defined by law. The insurer maintains that its industry is less risky than banking, and that imposing bank capital rules on life insurance companies could make it harder for Americans to buy insurance products.

MetLife will have 30 days to decide whether to appeal the regulators’ action in federal court.

MetLife was the fourth nonbank financial firm to be given the label by the council, a group of top regulators created by Congress in response to the 2008 financial crisis. The council is led by Treasury Secretary Jack Lew and includes Federal Reserve Chair Janet Yellen and Mary Jo White, chair of the Securities and Exchange Commission.

The group took the action on MetLife in a closed meeting, and it did not announce its decision.

Treasury Department spokeswoman Suzanne Elio said that in keeping with the council’s rules, "any vote on a final designation is generally announced to the public the following business day, to allow the company to prepare any public disclosures and communications."

Last year the council labeled AIG, General Electric Co.’s finance arm GE Capital and Prudential Financial Inc. as systemically important financial institutions.

The council proposed labeling MetLife in September and gave the company an opportunity to make its argument in a closed hearing. For the designation to become final, the council had to vote a second time, with at least two-thirds of the 10 voting members agreeing.

"Singling out two large life insurance companies (for the designation) will harm competition, lead to higher prices and less choice for consumers, and ultimately could result in less financial protection for middle-class families — who need it the most," MetLife said in its statement. It was referring to itself and Prudential.

MetLife announced last Friday that its board approved spending up to $1 billion more to buy back its own stock. It has spent $967.1 million of a $1 billion buyback program launched in June, which was MetLife’s first share repurchase plan in about six years. CEO Steven Kandarian, referring to the regulators’ actions, said the company wanted to reward MetLife’s shareholders even as its "approach to capital management remains cautious in light of regulatory uncertainty."

The biggest banks already were under the Fed’s supervision at the time of the financial crisis. A 2010 financial overhaul law brought strict new rules for them, such as on the amount of capital they must hold to cover potential losses. Nonbank companies that are designated as systemically important are also subject to those rules.

MetLife shares slipped 33 cents to $53.70 in aftermarket trading Thursday. They had risen $2.24, or 4.3 percent, to close at $54.03 in an exceptionally strong day in the stock market. MetLife shares have gained about 8 percent over the past 12 months.