Washington (CNN) The Senate intelligence committee Wednesday issued a subpoena to former National Security Adviser Michael Flynn for documents regarding his interactions with Russian officials.

The subpoena comes after Flynn's lawyer, Robert Kelner, alerted the panel that he would not provide documents in response to their April 28 request.

Flynn's lawyer declined comment to CNN Wednesday evening.

The subpoena also comes as Senate investigators have aggressively moved on their probe after months of groundwork, and just a few days after now-former FBI Director James Comey alerted the leaders of the intelligence panel the FBI was ramping up its own investigation.

Sen. James Lankford, a Republican on the Senate intelligence committee, told Fox News Wednesday evening that the panel had "subpoenaed a large number of documents."

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