The U.S. Court of Appeals on Tuesday rejected Paul Manafort's appeal of a judge's order sending him to jail before the trial, after Special Counsel Robert Mueller accused Donald Trump's former campaign chairman of attempting to tamper with witnesses, Bloomberg reported.

Manafort will have to stay in jail ahead of his money-laundering and obstruction of justice trial in Washington, which is scheduled to start September 17, it said.

He also faces tax and bank-fraud charges in Alexandria, Virginia. His trial on those charges begins Tuesday with jury selection.

Manafort is accused of tax evasion estimated at over $30 million during the period when he worked as a lobbyist for Ukraine's Party of Regions and former Ukrainian president Viktor Yanukovych.