The Senate Select Committee on Intelligence has ordered former White House National Security Adviser Michael Flynn to hand over records related to the Russian Federation investigation, according to a statement on the committee's website.
Representative Jim Himes, a Connecticut Democrat who is a member of the House intelligence committee that is also investigating Russian meddling in the election, said access to such financial records is one of the reasons lawmakers have been clamouring for Trump to release his tax returns.
To view the full article, register now. But he said that some people were not complying "so we were going to take next steps".
The Trump administration denies any collusion with Russian Federation.
Mr Trump said that he ultimately chose to fire Mr Flynn after learning that he had misrepresented the nature of a phone call he had during the presidential transition period with the Russian ambassador to the United States.
In an email, his lawyer Robert Kelner said they had no comment at this time on the subpoena.More news: Sushi lovers warned of parasite danger in raw fish
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"No reasonable person, who has the benefit of advice from counsel, would submit to questioning in such a highly politicized, witch-hunt environment without assurances against unfair prosecution", he said.
A former U.S. military intelligence chief, retired lieutenant general Flynn was generously paid to attend a gala of Russia's RT television in December 2015, where he sat with President Vladimir Putin, raising suspicions about his ties with Moscow.
"And that created a compromise situation, a situation where the national security advisor essentially could be blackmailed by the Russians".
Politico reports that Flynn's attorneys told the committee that the former general would not cooperate with the investigation unless he was granted immunity.
Some of Mr Trump's fellow Republicans, including Mr Burr, also expressed strong doubts about the timing of the president's action.