Workers at the world's biggest retailer, Wal-Mart, are seeking another US$62m in damages and interest related to their complaints of having to work off the clock and during rest breaks, reported Associated Press.

The workers in Pennsylvania have already been awarded $78.5m for their extra work but argue that about 125,000 plaintiffs in the class-action suit should receive an extra $500 each because the jury found Wal-Mart acted in bad faith.

Wal-Mart, however, denies wrongdoing and is appealing the original award.

Meanwhile, The Wall Street Journal has reported that the company will start switching many of its 1.3m workers to a flexible system based on the number of customers in stores at any given time.

The company reportedly began using the system for workers such as cashiers and accounting personnel last year.