BOSTON (AP) — The largest construction contractor on Boston's beleaguered Big Dig project filed for bankruptcy protection Monday, the first business day after federal prosecutors charged the company with lying about its work.

Modern Continental Co. made a Chapter 11 filing in federal bankruptcy court in Boston, alleging the state of Massachusetts had failed to pay it for construction work — work for which the state says it was overbilled. The firm has been paid more than $3 billion for Big Dig work, according to state records reviewed by The Associated Press.

The bankruptcy petition lists debts of $500 million to $1 billion owed to more than 200 creditors, and assets of $100 million to $500 million.