More than 1,100 gasoline station attendants in New Jersey have received $5.5 million in back wages and damages after a multiyear probe by the U.S. Department of Labor found the workers had not been paid the minimum wage and in some cases, overtime pay, the federal agency said Thursday.

"Our investigations of the New Jersey gas station industry found widespread violating of the federal Fair Labor Standards Act's minimum wage, overtime and record-keeping provisions," Mark Watson, regional administrator of the Wage and Hour Division in the Northeast, said in a statement.

Employees covered by the act must be paid no less than the federal minimum wage of $7.25 an hour, with non-agricultural and other non-exempt workers entitled to time-and-a-half of their regular rates for every hour they work above 40 hours a week.

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In the last fiscal year, the Labor Department recovered nearly $300,000 in back wages and damages for nearly 100 workers, or about $3,000 for each employee, at Shell, Exxon, BP and other leading gas vendors in the state.

The enforcement efforts have sparked change, according to the Labor Department, which said its investigators reported some gas stations hired more workers to avoid overtime violations and purchased time clocks to track hours worked.