Paul Manafort, the former campaign manager for Donald Trump, had three US passports, millions in assets and ties to Russian oligarchs, according to federal court documents related to his indictment on tax fraud and money laundering charges.

Manafort and associate Rick Gates pose a significant flight risk because of the serious nature of the charges, the strong evidence of guilt, their wealth and “their history of deceptive and misleading conduct”, federal prosecutors said in a filing on Tuesday in US district court for the District of Columbia.

Manafort, 68, and Gates, who also worked on Trump’s campaign, pleaded not guilty on Monday in a 12-count indictment, ranging from money laundering to acting as unregistered agents of Ukraine’s former pro-Russian government.

The charges came as part of federal special counsel Robert Mueller’s five-month-old investigation into alleged Russian efforts to tilt the 2016 presidential election in Trump’s favor and potential collusion by campaign aides.

The allegations are not related to campaign activities but reveal close ties to Russia and include activities from 2006 to 2017, which overlaps with the men’s work on Trump’s campaign.

The two men are under house arrest and have relinquished their US passports, with a $10m bond set for Manafort and a $5m bond for Gates.

“Both defendants have substantial ties abroad, including in Ukraine, where both have spent time and have served as agents of its government,” according to the government’s memorandum in support of the conditions of release.

“And both Manafort and Gates have connections to Ukrainian and Russian oligarchs, who have provided millions of dollars to Manafort and Gates.“

Manafort was a longtime US Republican operative before turning his attention to political consulting overseas.

Manafort submitted 10 passport application in the last decade and currently holds three US passports, the memo said.

Asked about the information in the memo, Manafort lawyer Jason Maloni told Reuters on Wednesday his client “looks forward to having these allegations tried before a judge and jury”.

The memo said Manafort’s financial assets were substantial but difficult to quantify because he listed figures on loan applications and other financial documents since 2012 that ranged from from $19m to $136m.

Manafort and Gates owned or controlled entities and accounts worldwide including in Cyprus, Grenadines, Seychelles and England, it said.