Alexandria, Virginia (CNN) A court hearing on Friday revealed that US authorities have previously unknown information about former national security adviser Michael Flynn doing secret work for the Turkish government "because of (his) relationship with an ongoing presidential campaign."

Flynn has previously only admitted publicly to filing false foreign lobbying disclosure documents regarding work for Turkey done by his lobbying group the Flynn Intel Group in 2016.

Prosecutors wrote to lawyers for Flynn's ex-lobbying partner Bijan Kian that the US government was "in possession of multiple, independent pieces of information relating to the Turkish government's efforts to influence United States policy on Turkey and Fethullah Gulen , including information relating to communications, interactions, and a relationship between Ekim Alptekin and Michael Flynn, and Ekim Alptekin's engagement of Michael Flynn because of Michael Flynn's relationship with an ongoing presidential campaign, without any reference to the defendant of FIG."

Kian's attorney Mark MacDougall read the statement at a court hearing Friday morning. He implied that the newly revealed information about Flynn -- which was not part of his admitted crimes in his plea deal with special counsel Robert Mueller -- may be classified.

Flynn's attorney Sidney Powell responded to the new accusation Friday, saying, "We have no idea what the government is talking about. It smacks of desperation."

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