WASHINGTON -- The Justice Department is asking a judge to dismiss a lawsuit by Donald Trump's former presidential campaign chairman.

Paul Manafort was indicted in October in special counsel Robert Mueller's (MUHL'-urs) Russia investigation. A suit Manafort filed last month challenges the scope of Mueller's appointment and authority.

The government says in a court filing Friday that a judge should throw out that suit.

Justice Department lawyers say federal courts are prohibited from interfering with ongoing criminal prosecutions - and that Mueller's been operating properly and not exceeded his authority.

The department says if Manafort believes he's being unfairly prosecuted, then he can file a motion in his criminal case to seek to have it dismissed.

Manafort is one of four people charged so far in Mueller's investigation.