The Office of Personnel Management is planning to reduce its call-center hours and halt overtime for workers who process federal-retiree pensions because of the government-wide spending cuts that took effect last month.

The agency expects the moves to save about $1.5 million in projected spending as it reduces its budget by about 5 percent under the sequester.

The OPM has struggled in recent years with a backlog of unresolved pension cases, but the numbers have steadily improved since January 2012, when then-Director John Berry hired more workers and increased overtime to address the issue, which he identified as his top priority that year.

The number of unprocessed claims stood at 61,000 when the OPM launched the initiative, but the number dropped to about 37,000 by last month.

The agency said in a statementMonday that “retirees should expect an increase in the time required to process their claims or respond to inquiries” as a result of the overtime suspension and reduced hours.

The National Active and Retired Federal Employees association described the OPM’s plan as an unfortunate effect of the sequester.

“Federal retirees have been waiting months for their benefits,” NARFE spokeswoman Jessica Klement said. “OPM has made great strides in reducing those delays, but this will reverse that trend.”

In 2012, the average time to process retirement claims was 156 days, although some retirees complained of waiting twice that long, according to Washington Post reports from that year.

Klement said the OPM backlog may be due in large part to the growing number of federal workers who are retiring. About one-quarter of federal and postal employees were eligible for retirement in 2011, according to OPM data from that year.

A House Oversight subcommittee plans to hold a hearing May 9 to discuss OPM operations, including the processing of retirement claims, which account for about 26 percent of the agency’s overall claims, according to subcommittee staff.

A NARFE representative is expected to testify during the hearing, Klement said.

The OPM’s call center was previously open from 7:30 a.m. to 7:45 p.m., but the new closing time will be 5 p.m.

The agency has not indicated when the overtime suspension, which took effect on Sunday, would end.