A year before his suicide in a cell inside New York's Metropolitan Correctional Center, Jeffrey Epstein was exchanging emails about his one-time friend, Donald Trump.

"You see, I know how dirty Donald is," he wrote on August 23, 2018.

The subject line of the email referenced a New York Times opinion piece about a case in which Trump's longtime fixer Michael Cohen pleaded guilty to campaign financing violations.

The note was sent to Kathryn Ruemmler, a former White House counsel under former president Barack Obama.

But it has now been released to the public by a US congressional committee in a deluge of emails and other messages, totalling some 20,000 pages, after a months-long stand-off in Congress.

The files belong to a collection held by Epstein's estate, which were subpoenaed by Congress in August and are separate from a trove of investigative materials on the financier held by the Justice Department.

In another exchange, Epstein attempted to pass a message to Russia's top diplomat suggesting that he could provide "insight" on Trump ahead of the president's meeting with Vladimir Putin in 2018.

"I think you might suggest to putin that lavrov can get insight on talking to me," Epstein wrote in a June 24, 2018, email to Thorbjorn Jagland, a former prime minister of Norway who was leading the Council of Europe at the time of the exchange.

Breaking down the newly released Epstein emails Donald Trump's relationship with Jeffrey Epstein is pushed back into the spotlight after he was named in several years-old emails unearthed by a congressional committee