WASHINGTON – A New Jersey-based construction and engineering company has been hit with the largest fines ever imposed on a contractor working in the war zones of Iraq and Afghanistan, after a whistle-blower revealed that the company had been overbilling the government.

The company, the Louis Berger Group, based in Morristown, N.J., will pay $18.7 million in criminal penalties and $50.6 million in civil penalties for overbilling the United States Agency for International Development for work in Afghanistan, Iraq and Sudan. As part of the civil agreement, the company will pay $14.2 million of the civil penalty in the next 30 days and the balance over the next four years.

In addition, two former company officials, Salvatore Pepe, 58, of Tuckahoe, N.Y., the former chief financial officer, and Precy Pellettieri, 54, of Rahway, N.J., the former controller, pleaded guilty on Friday to defrauding the government.

Paul J. Fishman, the United States attorney in New Jersey, said that over about 10 years, the company overcharged the government by $15 million to $20 million.