SAN FRANCISCO  Dell has been accused of withholding evidence, including e-mails among its top executives, in a lawsuit over faulty computers it sold to businesses, according to a filing made Thursday.

Advanced Internet Technologies filed a motion in Federal District Court in North Carolina asserting that Dell had deliberately violated a court order by failing to produce documents written by its executives, including the company’s chief executive and founder, Michael S. Dell.

The filing is the latest twist in a three-year-old lawsuit brought by A.I.T. that accuses Dell of selling at least 11.8 million faulty PCs over three years and then trying to hide problems with the computers from customers. A.I.T., an Internet services company, says it lost business as a result of the broken Dell machines.

Dell disputes the accusation. “We disagree with A.I.T.’s contention that we violated the discovery order and will be filing our response with the court soon,” said David Frink, a spokesman at Dell. “We take all court orders and our obligations to comply with them very seriously.”