Donald Trump and his legal team are exploring ways to hamper the investigation into alleged collusion with Russia and, in a worst-case scenario, nullify the repercussions, according to reports.

The US President's lawyers are developing a case against special counsel Robert Mueller and his team, compiling alleged conflicts of interest, three people with knowledge of the matter told AP.

And The Washington Post reported Mr Trump had queried his advisers about "his power to pardon aides, family members and even himself in connection with the probe".

Mr Mueller and congressional committees are investigating whether the President's campaign coordinated with Russia during the 2016 election.

Revelations about the Trump team's bid to counter the investigation come as the probe increasingly ensnares the President's family and close advisers, including son Donald Trump Jr and son-in-law and White House senior adviser Jared Kushner.

Mr Trump decried the probes as a partisan "witch hunt" and publicly challenged Mr Mueller, declaring this week the former FBI director would be crossing a line if he investigated his personal business ties.

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In an interview with the Post this week, Jay Sekulow, a member of the President's external legal team, pointed to Bloomberg News reports that Mr Mueller was scouring some of Mr Trump's business dealings, including the real estate mogul's sale of a $95 million mansion to a Russian oligarch in 2008.

Mr Sekulow told the Post the President and his lawyers were determined to ensure Mr Mueller did not stray outside his investigation's remit, and they would complain to Mr Mueller if needed.

"The fact is that the President is concerned about conflicts that exist within the special counsel's office and any changes in the scope of the investigation," The Post quoted him as saying.

"The scope is going to have to stay within his mandate. If there's drifting, we're going to object."

And Mr Sekulow told AP the lawyers would "consistently evaluate the issue of conflicts [in Mr Mueller's team] and raise them in the appropriate venue."

Two people with knowledge of that process said those efforts included probing the political affiliations of Mr Mueller's investigators and their past work history.

An adviser to the President who spoke to the Washington Post played down the claim Mr Trump was looking to pardon himself of any crimes, telling the Post Mr Trump had simply expressed curiosity about the reach of his pardoning powers and the Russia investigation.

"This is not in the context of, 'I can't wait to pardon myself'," the Post quoted the adviser as saying.

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ABC/AP