WASHINGTON – A U.S. contractor managing more than $1 billion in reconstruction contracts in Afghanistan faces federal criminal and civil investigations of claims that it overcharged the government for work, according to federal court documents.

Federal prosecutors are focusing on whether the Morristown, N.J.-based Louis Berger Group submitted inflated invoices to the U.S. Agency for International Development, which oversees many of the government’s international development projects.

The allegations come as U.S. officials spar with Afghan President Hamid Karzai over allegations of corruption in his government. Karzai has questioned U.S.-led probes of corruption in Afghanistan and argued that international donors have ignored corruption in billions of dollars worth of development projects they have handled.

Louis Berger has been a major player in U.S.-funded reconstruction projects in Iraq and Afghanistan, now leading a $1.4 billion USAID infrastructure project to build roads and power plants in Afghanistan.

Prosecutors acknowledged their ongoing criminal and civil investigations in response to a federal lawsuit filed last week by Derish Wolff, chairman of Louis Berger’s parent company, Berger Group Holdings. Wolff is attempting to block efforts to have his nearly one-third ownership stake in the company held in escrow following his resignation, which he said was forced as part of the company’s negotiations to end the federal inquiries.

Louis Berger has handled more than $2 billion worth of USAID contracts in Iraq and Afghanistan, agency records show. Its work in Afghanistan has included building schools, health clinics and roads and overseeing energy projects.

Court filings do not make it clear which projects prosecutors have focused on in their probes. Louis Berger officials declined to comment Saturday after issuing a statement noting that the company planned to cooperate with the investigations.