A group of former Pactiv Corp. employees have launched a boycott of the company and its parent company, Reynolds Group Holdings Ltd., protesting what they call “sweatshop conditions” at a Pactiv plant in Kearny, N.J.

The former workers in the plant’s packing department said they were given an increasingly heavy workload, required to work mandatory overtime and were reprimanded for taking bathroom breaks or sick leave. In July 2011, after workers had taken steps to unionize, Pactiv laid off about 60 percent of the department’s 100 employees, according to information on the group’s website, boycottreynolds.wordpress.com.

The workers, who are mostly Chinese and Latina women, are supported by the “Ain’t I a Woman!? Campaign,” an organizing arm of the Chinese Staff & Workers Association and National Mobilization Against Sweatshops.

According to the campaign, the department’s remaining employees were required to work 60-70 hours a week to handle the extra workload, and Pactiv hired temporary workers for the department, rather than recalling laid-off workers.

The campaign also says Pactiv offered displaced employees eight to 10 weeks of wages if they agreed to waive their legal right to challenge the layoffs.

Pactiv did not return calls seeking comment June 28.

Workers have filed charges against Pactiv with the National Labor Relations Board.

In a petition circulated by the campaign, workers are demanding, among other provisions, reinstatement with back pay for those workers who were laid off or fired.

Packaging giant Pactiv, based in Lake Forest, Ill., is North America’s largest thermoformer. The firm is owned by Reynolds Group Holdings Ltd. of Auckland, New Zealand, part of Rank Group Ltd.