Donald Trump's former national security adviser, Michael Flynn, has cut ties with White House lawyers.

Flynn is one of the highest profile individuals under investigation by special counsel Robert Mueller as part of efforts to reveal if there was collusion between Russia and the Trump campaign.

Until now, Flynn's lawyers had been sharing information with Trump's lawyers at the White House, but it is now understood that this deal has been called off, raising suspicion that he has reached a deal with the Mueller investigation, according to the New York Times.

Flynn was forced out of his position as Trump's adviser on national security after less than a month in the role after it was revealed that he lied to Vice President Mike Pence about his involvement with Russia.

While it hasn't been confirmed that there is any cooperation yet between Mueller and Flynn, the decision to part ways with the White House lawyers suggests that talks are at least underway between the two.

One other reason that Flynn may also be considering a deal, is to help his son, Michael Flynn Jr.

Flynn Jr. served as his father's chief of staff during several financial transactions that Mueller has honed in on, and in a bid to help his son, a deal of cooperation could be the Flynn's only choice to minimise charges for the pair of them.

If Flynn Sr was to be charged, then he would be the highest profile individual to be caught up in the investigation.

A retired three-star general, he was an early advocate of Donald Trump and was a respected hiring for the White House.

And unlike other arrests and charges made, Flynn was actually employed by the Trump presidency as opposed to the campaign or transition team.

In October, the former chairman of Donald Trump's presidential election campaign, Paul Manafort, was placed under house arrest after being indicted as part of an investigation into Russian collusion.

Manafort and his associate Rick Gates were indicted on 12 counts of conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading FARA statements, false statements, and seven counts of failure to file reports of foreign bank and financial accounts.

Meanwhile, one of Donald Trump's former top campaign advisers, George Papadopoulos, pleaded guilty to lying to the FBI during investigations into possible collusion between the Trump campaign and Russia.