Federal prosecutors have issued grand jury subpoenas as part of the ongoing probe of Russia’s interference in the 2016 presidential election, according to a new report.

The subpoenas to associates of former national security adviser Michael Flynn are seeking business records, CNN said Tuesday.

CNN confirmed with people familiar with the matter that the U.S. Attorney’s Office in Alexandria, Va., issued the subpoenas in recent weeks.

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The subpoenas are a significant escalation of the FBI’s broader investigation into possible ties between Russia and President Trump Donald John TrumpBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Military leaders asked about using heat ray on protesters outside White House: report Powell warns failure to reach COVID-19 deal could 'scar and damage' economy MORE’s 2016 campaign.

The news of subpoenas comes on the same night that Trump fired FBI Director James Comey.

The White House said Comey was fired at the recommendation of the Justice Department, but critics of the administration are questioning whether the action is related to the FBI's probe of Russian election interference and any possible ties between Trump's campaign and Moscow.