Lawyers for Donald Trump say he has the power to hire and fire as he sees fit, and have called into question the reliability of his former FBI director as they lay out their defence against allegations of obstructing justice, it was reported on Thursday.

The Wall Street Journal reported the President’s legal team submitted a memo to the special counsel leading the investigation saying he has authority under the constitution to dismiss the head of the FBI.

It also said another memo suggested James Comey, fired by Mr Trump in May, was the source of leaks to the news media and would make an unsuitable witness.

The details offer a glimpse into how Mr Trump’s lawyers plan to head off the investigation by Robert Mueller, the special counsel, which becomes bigger and broader all the time.