Cohen, who told the investigators that the plans had been scrapped in early 2016, admitted on Thursday that negotiations had in fact continued through June that year.

That means the Trump Organisation was continuing to pursue a business opportunity in Moscow deep into Trump's run for president - a deal that remained live at a time when Russians were seeking to make multiple inroads into the campaign and had, according to Mueller, began social media and hacking efforts to benefit Trump's campaign. Trump has publicly denied having any business with Russia at the time.

Shortly after the plea, Trump accused Cohen of lying to curry favour with prosecutors.

"This is a weak person and not a very smart person," Trump told reporters on Thursday as he departed the White House on his way to the G20 summit in Argentina. Cohen is trying to reduce his prison sentence "by making up a story," he continued. "Michael Cohen is lying."

Cohen, in his court appearance on Thursday, said he had discussed the deal with members of the Trump Organisation. "In fact, I took steps to and had discussions with Individual 1 about travel to Russia,' he told the court, referring to Trump.

Along with his plea, Cohen secured a formal cooperation deal with Mueller's team of investigators. The announcement came just days after Mueller's team scratched another high-profile cooperation agreement, with former Trump campaign chairman Paul Manafort, who prosecutors say lied to them multiple times.

It comes just days after Trump's legal team submitted written responses to questions from Mueller's office related to events that occurred before he took office and Russia-related topics.

Until now, Cohen had been operating without a formal cooperation deal. Cohen pleaded guilty earlier this year in Manhattan to campaign finance and tax violations, the result of an investigation into Cohen's business dealings that was referred by Mueller's team to federal prosecutors in New York. Following his plea, Cohen spent dozens of hours providing testimony to Mueller's investigators and other federal officials, a person familiar with the matter has said.

Cohen told the court he lied to Congress about Trump's Moscow tower in order to be consistent with his former boss's political positions. In early 2016, Trump repeatedly disavowed commercial ties between himself and Russia and claimed that all contact between his company and Russia had terminated.

Cohen told the Senate committee in September 2017 that a proposal to develop a Trump Tower in Moscow was "solely a real estate deal and nothing more". At the time, he told the investigators that the Moscow project ended "before the Iowa caucus and months before the first primary".

On Thursday, Cohen admitted: "I knew at the time in that I asserted that all efforts had ceased in January 2016, when in fact they continued until June 2016," Cohen said. That same month, members of Trump's campaign committee held a now-infamous meeting in Trump Tower with a Russian lawyer who they were told would deliver "dirt" on Democratic candidate Hillary Clinton.

Trump's open admiration of Putin has invited speculation among his critics that it's related to secret financial interests he has there. Trump has issued repeated denials. 'I HAVE NOTHING TO DO WITH RUSSIA - NO DEALS, NO LOANS, NO NOTHING!' he wrote on Twitter in January 2017, shortly before he was inaugurated.

Cohen provided a written statement to the House intelligence committee in August 2017 that said he had discussed a proposal to build a hotel and condominium tower in Moscow with Donald Trump on three occasions.

Cohen said the Trump Organisation signed a non-binding letter of intent with Moscow-based I.C. Expert Investment Company and solicited building designs from architects and engaged in preliminary financing discussions. But the project ultimately fizzled, Cohen told the committee, and Trump wasn't involved in the decision to abandon the project.

Cohen worked on the deal with Felix Sater, a Russian-born developer and US citizen, who served as a deal broker on the project. Sater, who served time in prison for assault and worked as an informant to US prosecutors investigating the mob's role on Wall Street, had helped Trump on a hotel and condominium project in Manhattan.

Trump continued bashing the Mueller probe on Thursday, writing on Twitter: "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?"

Bloomberg