Michael Cohen, US president Donald Trump's former lawyer, has claimed that Mr Trump's involvement with a real-estate deal in Russia continued well into the 2016 presidential campaign, contrary to his previous statements.
In the latest twist in the Mueller investigation into Russian interference in that election, Mr Cohen made a surprise appearance in a New York courtroom on Thursday, two weeks before his scheduled sentencing date on December 12th.
He admitted to lying to Congress about what he knew about Mr Trump's discussions about a hotel project in Moscow in the months leading up to the 2016 presidential election.
While he previously stated in written testimony to the House and Senate intelligence committees that discussions about a proposed Trump Tower hotel in Moscow ended in January 2016, in fact those negotiations had continued right up to the summer, he said.
The 52-year-old lawyer said in court filings signed by special counsel Robert Mueller that he had advised Mr Trump and members of his family more than three times of the discussions.
He also said that he had offered to travel to Russia to discuss the deal, and a Russian associate Felix Sater had suggested that Mr Cohen might get an audience with President Vladimir Putin or prime minister Dmitry Medvedev.
Mr Trump has repeatedly said that he has no business dealings with Russia, but the latest revelations suggest that he had in fact a financial interest in Russia during the presidential campaign.
The news could be particularly significant given that Mr Trump consistently called for a more conciliatory US foreign policy towards Russia during the presidential campaign, and successfully lobbied for a rethink on Ukraine policy at the Republican national convention in 2016.
But Mr Trump defended his business dealings in Russia as he left Washington for the G20 summit in Argentina. Describing his one-time ally as a "weak person, and not a very smart person", he said Mr Cohen had lied in court to get a reduced sentence.
“He’s lying about a project that everybody knew about it,” he said. “He is lying very simply to get a reduced sentence.”
Referring to the proposed Trump Tower project in Moscow, he said: “I decided ultimately not to do it. If I did do it there would be nothing wrong.”
He said he had a right to continue to pursue business deals while he was running for president. “I ran a business. I often joke about the fact that I was the only person who campaigned and simultaneously ran a business.”
Asked why he had hired Mr Cohen given his views on him, Mr Trump replied: “Because a long time ago he did me a favour.”
Mr Cohen, who was Mr Trump’s long-term fixer and personal lawyer before he was indicted in April, declined to comment to reporters as he left the courthouse in lower Manhattan on Thursday.
“Mr Cohen has co-operated. Mr Cohen will continue to co-operate,” his lawyer said as he left the courtroom. Earlier in the day, Mr Trump continued his Twitter tirade against the special counsel investigation.
“When will this illegal Joseph McCarthy style Witch Hunt, one that has shattered so many innocent lives, ever end-or will it just go on forever? After wasting more than $40,000,000 (is that possible?), it has proven only one thing-there was NO Collusion with Russia. So Ridiculous!”
Mr Trump is understood to have provided written responses last week to the special counsel’s office to a series of questions related to the Russia investigation.
Mr Trump later announced in a tweet from Air Force One that he was cancelling his proposed bilateral meeting with Mr Putin on Saturday at the G20 summit over Russia's failure to return seized personnel and ships to Ukraine.
“I look forward to a meaningful Summit again as soon as this situation is resolved!” he tweeted.