FILE PHOTO: The seal of the U.S. Securities and Exchange Commission hangs on the wall at SEC headquarters in Washington, DC, U.S., June 24, 2011. REUTERS/Jonathan Ernst/File Photo

(Reuters) - MetLife Inc said on Monday the U.S. Securities and Exchange Commission was looking into the insurer’s failure to pay some workers’ pensions.

MetLife, in a statement, said the SEC’s enforcement staff has inquired about payments that the insurer failed to make for people who receive a type of annuity benefit from the company via its retirement business. Less than 5 percent of 600,000 people are affected, the company has said.

The New York insurer estimated increasing total reserves by between $525 million and $575 million on a pre-tax basis, resulting in a hit to fourth-quarter earnings of $135 million to $165 million.

Last month, MetLife said it failed to pay pensions to possibly tens of thousands of people and would have to strengthen its reserves because of the costs of finding and repaying them.

“To date, MetLife is not aware of any intentional wrongdoing in connection with this matter,” the company said on Monday, adding that it was responding to the SEC’s questions.

MetLife shares closed at $54.40, down 0.7 percent.

The insurer is reviewing its processes and procedures for identifying people who receive the type of group annuity benefit at issue as well as pension beneficiaries, it said.

Regulators in Massachusetts and New York state said in December they were probing the pension payment issue. [L1N1OI197]

MetLife has postponed its fourth-quarter earnings report and conference call, which had been scheduled for this week, to Feb. 13 and 14, respectively, the company said.