Amazon.com was accused by officials of violating the terms of a U.S. labor board settlement, breaching a 2021 agreement which required the online retailer to let workers unionize.

The company has been feeling the pinch of unionization efforts. Last year, workers at an Amazon warehouse in New York City voted to form the first union at the company.

The settlement, aimed at protecting workers, had required the company to let employees who were done with their shifts to access certain facilities on its premises in order to organize unions, a complaint by a regional director of the National Labor Relations Board said on Thursday.

"We've fully complied with the settlement agreement, which we voluntarily entered into in December 2021. This complaint has no merit and contradicts the very same regional office who confirmed our full compliance with the agreement and closed the cases over a year ago," an Amazon spokesperson said.

Separately, the Teamsters union on Friday picketed outside two Amazon warehouses in Los Angeles.

Some Amazon delivery drivers and dispatchers have been on strike at 16 of the company's warehouses across the country for nearly three months, protesting against the online retailer's labor practices, alleging "low pay and dangerous working conditions".

(Reporting by Samrhitha Arunasalam in Bengaluru; Editing by Shounak Dasgupta)