Citigroup Inc. plans to lay off 100 employees in its Reckson Plaza office in Uniondale, the bank said in a regulatory filing Tuesday.

The bank cited "economic" reasons for the layoff, which is part of a larger plan to cut about 5,000 employees because of volatile financial markets and declining trading and investment fees.

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"These actions were part of a restructuring plan previously announced at the end of 2011," the bank said in a statement Tuesday.

The Uniondale workers are part of a unit that focuses on consumer operations, such as processing statements. The office will remain open, staffed with workers in other operations, but Citigroup declined to say how many would continue there.

The Worker Adjustment and Retraining Notification Act filing said that the banking company began notifying the Uniondale employees on July 2 about the layoff and that the process would continue through Dec. 3. The company expects to complete the layoffs by March 3.

Citigroup has 261,000 employees worldwide, according to its latest Securities and Exchange Commission filing. The bank declined to say how many people it employs on Long Island.

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New York's WARN Act requires private-sector employers with at least 50 full-time employees to give employees a written, 90-day advance notice of a plant closing or mass layoff.