Securities regulators are investigating possible "systems and controls'' failings at a brokerage division of

MetLife

(MET) - Get Report

, the nation's largest life insurer announced late Wednesday.

The New York-based insurer disclosed the investigation by the

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Securities and Exchange Commission

in a corporate filing after the close of the trading day. The investigation focuses on MetLife's New England Securities division and potential problems in asset allocation decisions concerning some 6,000 active and closed customer accounts.

In a press release, MetLife estimates that it will take between $3 million and $11 million to rectify any mistakes made in those customer accounts.

The brokerage division is part of MetLife's New England Life Insurance subsidiary. News of the SEC investigation comes a day after MetLife disclosed an accounting problem at New England Life and fired several employees.

The accounting problem forced MetLife to restate its second-quarter earnings, which the insurer released a week earlier. The insurer said it would have to take a $33 million aftertax charge to correct that error, which stemmed from the improper booking of expenses at New England Life.

MetLife spokesman John Calagna said the problems at the brokerage division are unrelated to the accounting errors and stemmed from a glitch in a software program used by the brokerage to allocate shares to mutual fund customers. He said MetLife officials detected the problem in March and notified the SEC, which only recently began a formal investigation into the matter.