President Donald Trump has started what is expected to be a busy day for special counsel Robert Mueller’s Russia investigation by launching a Twitter broadside against the prosecutor and his team.

Mr Mueller faces court deadlines in two pivotal cases on Friday, and ex-FBI Director James Comey is set to appear before politicians on Capitol Hill.

Mr Trump has made little secret of his frustration with the swirling probe into Russian election interference and potential misdeeds committed by those in his orbit and is seeking to undermine the legitimacy of Mr Mueller’s investigation.

Mr Trump tweeted: “Robert Mueller and Leakin’ Lyin’ James Comey are Best Friends, just one of many Mueller Conflicts of Interest.”

Mr Mueller’s investigation has produced dozens of criminal charges and four guilty pleas from Trump associates.

Mr Trump also argues his deputy attorney general, Rod Rosenstein, is “totally conflicted”.

Mr Rosenstein oversaw the probe until last month.