Alexandria (United States) (AFP) - Closing arguments wrapped up in the trial of Paul Manafort on Wednesday, with prosecutors accusing Donald Trump's former campaign chief of weaving a web of lies to avoid paying taxes.

Defense attorneys sought to cast doubt on the credibility of the government's star witness in the case, which stems from Special Counsel Robert Mueller's probe into Russian interference in the 2016 presidential election.

"This case is littered with lies," assistant US attorney Greg Andres told the six-man, six-woman jury on day 12 of Manafort's trial for tax evasion and bank fraud.

"Mr Manafort lied and lied again" as he sought to conceal tens of millions of dollars he received between 2005 and 2014 from Russian-backed politicians in Ukraine, Andres said.

"Mr Manafort lied to keep more money when he had it," Andres told a packed federal courtroom in Alexandria, Virginia. "And he lied to get more money when he didn't."

Manafort, 69, a Republican political consultant and lobbyist, is charged with 18 counts of tax evasion and bank fraud.

He is not charged with any crimes related to his brief time as Trump's campaign chairman, but the trial is seen as an important test for the Mueller investigation, which the president has repeatedly denounced as a political "witch hunt."

Andres said Manafort filed false tax returns between 2010 and 2016 to hide his earnings from US tax authorities.

'He owned these accounts'

The money from Ukrainian politicians was deposited in 31 foreign bank accounts, most of which were in Cyprus, and Manafort repeatedly failed to report their existence to his bookkeeper, his accountants and the Internal Revenue Service, the prosecutor said.

"He owned these accounts, he controlled them, he moved the money at will," Andres said as Manafort, dressed in a blue suit, jotted down the occasional note at the defense table.

"You didn't need to be a tax expert" to know that the money should have been reported, Andres said.

Manafort also filed false statements to obtain millions of dollars in loans from banks when he was facing financial difficulties, he said.

The prosecution's key witness against Manafort was his long-time deputy, Rick Gates, who outlined for the jury how he helped his boss shield his earnings from the US tax authorities.

Defense attorneys, who did not call any witnesses of their own, sought to paint Gates as a liar and a thief, pointing out that he had pleaded guilty to his own crimes in the hopes of receiving a lesser sentence.

"The government was so desperate to make a case against Mr Manafort that it made a deal with Rick Gates," defense attorney Kevin Downing said. "This was someone Paul trusted."

During his three days of grueling testimony, Gates, 46, acknowledged stealing hundreds of thousands of dollars from Manafort and having an extramarital affair a decade ago.

Andres countered that the defense focus on Gates was a diversion.

"The defense wants you to believe this case is about Rick Gates," he said. "They want to distract you.

"We don't ask you to like him," the prosecutor said, appealing to the jury to compare Gates' testimony to that of the more than 20 other witnesses called against Manafort.

Hoping for a pardon?

"Does the fact that Mr Gates had an affair more than 10 years ago make Mr Manafort less guilty?" he asked.

Arguing for acquittal, Richard Westling, another Manafort attorney, said the government had failed to prove Manafort's guilt beyond a reasonable doubt.

Andres disagreed.  

"The defense is asking you to ignore your common sense," he told the jury. "All the evidence shows Mr Manafort is guilty and guilty as charged."

Prosecutors provided evidence during the trial of Manafort's years of lavish spending -- millions of dollars on luxury houses, cars, antique rugs and clothes, including an $18,500 python jacket.

But Andres said the case was "not about his wealth."

"It's not a crime in this country to be wealthy," he said. "Mr Manafort knew the law and he violated it anyway."

While Gates and several others indicted by the special counsel's office pleaded guilty, Manafort insisted on going to trial.

Manafort, who worked on the presidential campaigns of Republicans Gerald Ford, Ronald Reagan, George H.W. Bush and Bob Dole, was Trump's campaign chairman from May to August 2016.

He was forced to step down amid questions about his work for Ukraine's former pro-Russian leader Viktor Yanukovych and legal experts say he may be holding out hopes of a pardon from Trump.