A federal judge has rejected a request from Special Counsel Robert Mueller's prosecutors, dealing the probe a legal blow.

US District Court Judge Dabney Friedrich issued the brief order on Saturday evening, denying Mueller's request to delay the scheduled Wednesday arraignment for Concord Management and Consulting, Politico reported.

Concord is one of the three Russian companies and 13 Russian individuals that were accused in a February indictment of using social media to inflame divisions during the 2016 election.

Prosecutors expected the case to proceed without any appearance or defense from the foreign defendants - and were stunned when two lawyers appeared on Concord's behalf last month and began demanding extensive document production from the Mueller probe.

A federal judge has rejected a request from Special Counsel Robert Mueller's prosecutors, dealing the probe a legal blow

Suddenly, it seemed it might be a bid to force Mueller to turn over sensitive documents, and perhaps even force prosecutors into an embarrassing dismissal of charges that they had never planned to press in open court.

In a motion late Friday, Mueller’s prosecutors disclosed that Concord’s attorneys, DC-based Eric Dubelier and Kate Seikaly, had made a slew of discovery requests demanding nonpublic details about the case and the investigation.

The prosecutors asked the court for a delay in order to determine whether Concord had been properly served, and verify that Dubelier and Seikaly were authorized to represent the company.

The defense attorneys blasted back in a response to the motion on Saturday, accusing the Mueller team of 'pettifoggery'.

'Defendant voluntarily appeared through counsel as provided for in [federal rules], and further intends to enter a plea of not guilty,' the filing read.

'Defendant has not sought a limited appearance nor has it moved to quash the summons. As such, the briefing sought by the Special Counsel’s motion is pettifoggery.'

Judge Friedrich's order means the arraignment will continue as scheduled on Wednesday.

The three companies named in the indictment are all reportedly controlled by Yevgeny Prigozhin, a Russian businessman known as Russian President Vladimir Putin's 'chef'.

Prigozhin is also one of the 13 individuals criminally charged in the case.