Washington, Nov 27 (AFP) Donald Trump's former campaign chairman Paul Manafort violated his plea agreement by lying to investigators, prosecutors said Monday, as another former aide began serving a jail sentence for making false statements to the FBI.

Manafort had agreed to cooperate with special counsel Robert Mueller's investigation of possible collusion between the Trump campaign and Russia as part of a plea deal in September.

"After signing the plea agreement, Manafort committed federal crimes by lying to the Federal Bureau of Investigation and the Special Counsel's Office on a variety of subject matters, which constitute breaches of the agreement," prosecutors said in a court filing.

"A breach relieves the government of any obligations it has under the agreement." In the same joint status report filing, Manafort's legal team pushed back against the government's assertion.

"Manafort has provided information to the government in an effort to live up to his cooperation obligations," it said.

"He believes he has provided truthful information and does not agree with the government's characterization or that he has breached the agreement."

Manafort, who worked for the Trump campaign for nearly six months in the middle of 2016, agreed to plead guilty to one count of conspiracy against the United States and another count of obstruction of justice in a deal to avert a second trial on money laundering and illegal lobbying charges.

He was already convicted in a separate jury trial on eight counts related to financial fraud in August, but those charges, as well as the counts covered in the plea deal, were unrelated to the campaign.

Instead, they derived from his work for former Ukrainian president Viktor Yanukovych and his pro-Moscow political party between about 2005 and 2014.

As prosecutors accused Manafort of lying, George Papadopoulos -- the former Trump campaign aide whose Russia contacts set off the collusion investigation -- entered a minimum security unit to start serving out his two-week jail sentence at the Oxford, Wisconsin federal prison.

Papadopoulos was an obscure oil industry analyst when he joined the Trump campaign's foreign policy advisory team in March 2016.

Based in London, he made contacts with what he believed were important Russian and Russia-linked officials, who through him offered the Trump campaign a meeting between candidate Trump and Russian President Vladimir Putin.

One, a mysterious professor by the name of Joseph Mifsud, told Papadopoulos that Moscow had dirt on Trump's election rival, Democrat Hillary Clinton.

After an allegedly drunken Papadopoulos related the conversation to an Australian diplomat who passed the information on through intelligence channels, the FBI opened an investigation into contacts between the Trump campaign and Russia.

Emails and testimony by other witnesses showed that Papadopoulos had repeatedly reported his Russia contacts and meetings to the Trump campaign, raising suspicions of collusion.

One week after Trump took office, the FBI conducted an interview with Papadopoulos during which he lied about his contacts, including with Mifsud, according to federal charges.

He pleaded guilty in October 2017 and pledged to cooperate with the Mueller probe, and was later sentenced after expressing his remorse that he "lied in an investigation that was important to national security."

But immediately after that, Papadopoulos declared he had been entrapped by US and foreign intelligence services and alleged that Mifsud was a CIA operative who was part of a broader campaign to damage Trump. (AFP) SMJ

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