Michael Flynn at the White House in Washington DC on 22 January 2017.

Donald Trump’s former national security adviser Michael Flynn was expected to plead guilty on Friday morning to making false statements to FBI agents in their investigation of Russian meddling in the 2016 presidential election.

About four days after Trump became president, Flynn made “materially false, fictitious and fraudulent statements” to law enforcement about a meeting he had with then-Russian ambassador Sergey Kislyak, according to court documents.

Flynn was scheduled to appear at a plea hearing at 10.30am in Washington DC.

Flynn is at the center of a broader investigation by special counsel Robert Mueller into links between the Trump campaign and Russian operatives. It had appeared that Mueller’s team was seeking a deal of some kind to win Flynn’s cooperation in that investigation.

Flynn falsely denied to investigators that he had asked Kislyak in a meeting during the presidential transition to refrain from escalating the situation after the United States imposed new sanctions on Russia, and falsely denied that he had asked the ambassador in a separate meeting to delay a vote on a UN resolution, according to court documents.

Flynn further failed to recall being told by Kislyak that Russia had decided to moderate its response to the new sanctions at Flynn’s request, the documents said.

Flynn, who had failed to declare payments from Turkish and Russian sources and who was reportedly under investigation for an alleged role in a kidnapping plot, appeared vulnerable to much more serious charges than making false statements.

Anne Milgram, who has worked closely in the past with Mueller and his team as a former attorney general for the state of New Jersey and former federal prosecutor, said that prosecutors’ decision to charge Flynn with a relatively minor offense indicated that a deal for Flynn to cooperate with prosecutors had been struck.

“And that was very quick,” Milgram said in an email.

The Trump campaign has denied coordinating with Russia during and after the presidential campaign, even as evidence of at least 19 in-person meetings between the two sides has emerged and Mueller’s team has uncovered high-level conversations inside the campaign about the contacts.

Flynn resigned after 24 days as national security adviser when US surveillance records came to light indicating that he had discussed sanctions with Kislyak, despite a public denial at the time by vice president Mike Pence that such a discussion had taken place.