Former Trump campaign manager Paul Manafort departs from U.S. District Court in Washington, U.S., February 28, 2018.

"Mr. President, did you know that Paul Manafort was sharing polling data from your campaign with the Russians?" a reporter asked Trump at the White House on Thursday.

The disclosure that Manafort had given Kilimnik polling data is the strongest piece of public evidence that a high-ranking Trump campaign official may have been coordinating with Russians in an illegal effort to get Trump elected. Such data could have been used by Russia as part of a broad-ranging scheme, which involved bogus social media accounts, to manipulate public opinion in Trump's favor.

Trump's comment came two days after Manafort's criminal defense lawyers inadvertently disclosed that special counsel Robert Mueller has accused Manafort of lying about sharing such data with alleged spy Konstantin Kilimnik.

President Donald Trump on Thursday said he knew "nothing" about his then-campaign chief Paul Manafort sharing polling data with an alleged Russian spy during the 2016 presidential campaign.

Trump replied: "No, I didn't know anything about it."

"Nothing about it," the president added.

Manafort's defense team also on Tuesday accidentally disclosed that Mueller has accused him of misleading the special counsel's office about discussions that Manafort had with Kilimnik during the campaign about a possible peace plan for Ukraine.

Russia, which annexed the Crimea from Ukraine in 2014, was anxious to have a peace deal in order to get out from under U.S. sanctions that were imposed on Russia for its aggression.

Mueller has also accused Manafort of being deceptive about a meeting the former Trump campaign boss had with Kilimnik in Madrid, Spain, according to Manafort's lawyers.

Manafort pleaded guilty last summer to multiple crimes related to his consulting work and income from a pro-Russia political party in Ukraine. That work predated the longtime Republican operative's five-month tenure with the Trump campaign in 2016.

Mueller has charged that Kilimnik, who worked for Manafort for years, tried with Manafort to tamper with potential witnesses against Manafort.

Mueller has alleged that Kilimnik — who remains at large — has ties to "a Russian intelligence service and had such ties in 2016."

As part of his plea deal with Mueller, Manafort agreed to cooperate with the special counsel's investigation.

Mueller is probing Russian interference in the 2016 election, possible involvement by members of the Trump campaign in such illegal interference and possible obstruction of justice by Trump.

Trump has denied any wrongdoing by his campaign and by himself.

Mueller last fall accused Manafort of breaking his plea deal by lying to the special counsel's team. The details of those alleged lies were not known until Manafort's lawyers filed a document Tuesday in federal court in Washington. Much of that document was public, but the details of Mueller's claims of lies by Manafort were blacked out.