US President Donald Trump had conversations about a proposed project to build a Trump Tower in Moscow throughout the 2016 presidential campaign, far later than previously acknowledged, his lawyer said today.

Mr Trump's conversations with his then personal lawyer and fixer, Michael Cohen, who was spearheading the negotiations in Moscow, continued throughout the year until October or November 2016, Rudy Giuliani said.

"It's our understanding that they went on throughout 2016 - there weren't a lot of them, but there were conversations," the former New York mayor said on NBC's Meet the Press.

"Can't be sure the exact dates, but the president can remember having conversations with him about it," he said.

Rudy Giuliani

Mr Cohen, who was sentenced to three years in prison for an assortment of felonies, has pleaded guilty to lying to Congress in 2017 when he testified that the negotiations had ended by January of 2016.

In fact, he later admitted, they had gone on much longer, until June of 2016, when Mr Trump had become the presumptive nominee of the Republican Party.

The latest disclosure extends that timeline right up to the presidential elections in November.

The Trump Tower project has been a subject of scrutiny because Mr Trump had denied any business dealings with the Russians.

He has since acknowledged that Mr Cohen pursued a deal with the Russians well into 2016, but has insisted there was nothing wrong with seeking business opportunities while running for office.

Mr Giuliani said Trump had fully answered questions about the Trump Tower project put to him by Special Counsel Robert Mueller.

Mr Mueller is investigating whether the Trump campaign colluded with a Russian effort to sway the 2016 elections in the Republican's favour, as well as possible obstruction by the president.

Mr Giuliani portrayed Trump's role in the Moscow negotiations as that of a passive participant who was too busy running for president to pay much attention to it.

Michael Cohen

"It was Michael Cohen driving the project," he told CNN in a separate interview on its State of the Union show.

Candidate Trump, he said, was "tied up 18 hours a day with that (the campaign). If he could devote a minute a day to this, it would be a lot. A minute here, a minute there.

"Your recollection of that is not going to be as strong. The guy running it is going to remember it," he said.

Mr Cohen is scheduled to testify before the House Oversight Committee on February 7.