Massachusetts securities regulators have begun an investigation into MetLife’s failure to pay thousands of workers’ pensions.

In a filing made on Friday, MetLife disclosed that it failed to pay monthly pension benefits to workers within its retirement business unit. MetLife reported that it is in the process of trying to locate pensioners to whom it has failed to pay monthly pensions. MetLife states in its filing those pensioners “have moved jobs, relocated, or otherwise can no longer be reached.”

The disclosure by MetLife does not state the exact number of retirees who are impacted, what efforts MetLife has made to find correct addresses, how long the problem has been going on, or when and how MetLife learned of the problem.

“MetLife acquired the pension payment obligation from the retirees’ former employer and now bears the responsibility of making sure that retirees receive their pension checks,” Massachusetts’ top securities regulator, William Galvin, said in a statement. “Retirees cannot afford to have glitches with their pension checks. I want to uncover why this occurred and how MetLife is going to rectify the problem for the retirees.”

The Massachusetts Securities Division sent out an inquiry letter on Monday seeking, among other things, how and when the glitch was discovered, information on the plans involved, the number of individual accounts affected by the agreement, and each accountholder’s name and address.

According to Reuters reports, MetLife believes the group missing out on the payments represented less than 5% of about 600,000 people who receive benefits from the company via its retirement business. Those affected generally have average benefits of less than $150 a month, according to MetLife.

— Related on ThinkAdvisor: