FILE PHOTO: Paul Manafort, U.S. President Trump's former campaign manager, arrives with his wife Kathleen for an arraignment hearing at the federal courthouse in Alexandria, Virginia, U.S., March 8, 2018. REUTERS/Joshua Roberts

(Reuters) - Robert Mueller, the U.S. Justice Department’s special counsel, is specifically authorized to investigate allegations that Paul Manafort, President Donald Trump’s former campaign chairman, colluded with Russia to interfere with the 2016 presidential election, a court filing showed late on Monday.

They court documents also show that Mueller is specifically authorized to investigate Manafort’s ties to Ukraine’s former pro-Russia government.

The documents were filed in response to a motion by Manafort challenging Mueller’s authority to prosecute him.

Manafort does not currently face charges related to the 2016 presidential election or Russian interference. But he is charged with bank fraud, filing false tax returns, conspiring against the United States by plotting to launder money and failing to register as a foreign agent when he lobbied for the former Ukraine government.

His court action sought to have those charges dismissed, arguing that Mueller lacked the authority to investigate his dealings with Ukraine.

No one on either side of the case was available for comment early Tuesday.

Trump has frequently declared no collusion occurred between his campaign and Russia.