In this file photo taken on Thursday, Dec. 10, 2015, Russian President Vladimir Putin, center right, with retired U.S. Lt. Gen. Michael T. Flynn, center left, and Serbian filmmaker Emir Kusturica, obscured second right, attend an exhibition marking the 10th anniversary of RT (Russia Today) 24-hour English-language TV news channel in Moscow, Russia.

Russian state-owned network RT paid more than $45,000 for Michael Flynn to travel to Moscow to speak in December 2015, Yahoo News reported, citing a document obtained by a congressional committee.

At the time, Flynn was a retired lieutenant general and former Defense Intelligence Agency director. He would later become President Donald Trump's campaign advisor and first national security advisor, until he was forced to resign over misstatements about his communications with a Russian diplomat.

Flynn went on a three-day trip with his son, Michael Flynn Jr., staying in a five-star hotel at the Russian government's expense for RT's 10th anniversary celebration in 2015, according to Yahoo. Flynn got nearly $34,000 from the engagement, the report said. In addition, it said, his speaking agency received a 25 percent commission.

Some Democrats allege that Flynn's trip appeared to run afoul of rules barring former military officers from accepting consulting fees, gifts or travel expenses from a foreign government, Yahoo said. It also raises questions about what Trump knew about Flynn's Russian connections before hiring him.