Mike Pence was kept in the dark about the Justice Department's assessment of Michael Flynn

Vice President Mike Pence was informed about a Justice Department assessment of former national security adviser Michael Flynn more than two weeks after President Donald Trump was briefed, according to a report from NBC News.

The DOJ's assessment, as reported by The Washington Post on Monday, determined Flynn may be susceptible to blackmail by Russia after he discussed US sanctions against the Kremlin with a Russian ambassador.

Sally Yates, who was deputy attorney general at the time the assessment was compiled, said the nature of Flynn's calls with Russia were "highly significant" and "potentially illegal."

Pence's press secretary, Marc Lotter, told NBC News that Pence was briefed on the DOJ's findings on February 9, while Trump was told two weeks earlier, on January 26. Reasons for the timing gap are unclear.

Pence's briefing happened the same day The Post published a story citing senior US officials who told the newspaper Flynn indeed discussed US sanctions in phone calls with Russian ambassador, Sergey Kislyak, contradicting Flynn's earlier public denials.

That information was revealed after Pence repeated Flynn's denials, citing conversations he had with Flynn, during television interviews in January.

Republicans in Congress are pushing for a full investigation into Flynn's associations with Russia.