(CNN) A Russian company indicted by special counsel Robert Mueller says it plans to plead not guilty to the criminal charge that it engaged in a fraud conspiracy to influence the 2016 US presidential election.

In a court filing in federal court in Washington, DC, on Saturday, US-based defense attorneys for the Russian company, Concord Management and Consulting, snapped back at Mueller's office by calling the lawyering by one of the prosecutors "pettifoggery."

The federal judge on Saturday also denied prosecutors' request to postpone Concord's initial appearance, scheduled for Wednesday. The special counsel's office had asked to reschedule Concord's appearance because it hadn't properly served the company with a summons.

"I find it disturbing that in your first communication you are already behaving in a manner that is inconsistent with the practices of the Department of Justice," Eric Dubelier, a US attorney from the law firm Reed Smith that represents Concord, wrote to prosecutor Jeannie Rhee, according to an April 20 email he submitted to the court.

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