(ABC News) -- Sources with direct knowledge confirm to ABC News that President Donald Trump’s eldest son, Donald Trump Jr., communicated with representatives from WikiLeaks during the 2016 campaign via private message on Twitter.

The sources confirm to ABC News that WikiLeaks made contact with Trump Jr. in late September 2016 and continued into the first half of this year. One source says the conversations were heavy in one direction with WikiLeaks sending many messages to Trump Jr. and the president’s son responding on a limited basis, often ignoring them.

A source close to Trump Jr. tells ABC News they believe after Wikileaks’ initial message to him, he did send an email to campaign officials including Steve Bannon, Kellyanne Conway, Brad Parscale, and Jared Kushner sharing that Wikileaks had made contact, as first reported by The Atlantic.

The sources also confirm to ABC News the correspondence was turned over by Trump Jr. to congressional investigators as part of the ongoing Russia probe.

Alan Futerfas, Trump Jr.’s lawyer said in a statement to ABC News that his client has cooperated with the various congressional committee investigations.

“Over the last several months, we have worked cooperatively with each of the committees and have voluntarily turned over thousands of documents in response to their requests,” Futerfas wrote. “Putting aside the question as to why or by whom such documents, provided to Congress under promises of confidentiality, have been selectively leaked, we can say with confidence that we have no concerns about these documents and any questions raised about them have been easily answered in the appropriate forum.”

Rep. Adam Schiff, D-California, the top Democrat on the House Intelligence Committee, says the direct message exchange is "yet another indication of the campaign's willingness at the very highest levels to accept foreign assistance."

"This is yet another indication of the campaign’s willingness at the very highest levels to accept foreign assistance, to accept assistance here with a cutout of the Kremlin that is publishing stolen documents that were obtained by a Russian hacking of Hillary Clinton’s campaign," he told ABC News.

"We just see this web of connections becoming more and more extensive."

WikiLeaks founder Julian Assange Tweeted that he couldn't confirm the communiques to Trump Jr.