The goal of the special counsel probe, he said, was to determine whether there was collusion between Trump associates and Russian Federation to do so.
Mr Trump said in a statement on Wednesday night (local time) that "a thorough investigation will confirm what we already know - there was no collusion between my campaign and any foreign entity".
In a pair of Twitter posts on Thursday morning (local time), Mr Trump made clear he was unhappy with the latest development to roil his administration.
On May 10, the day after he fired Comey, Trump met with Russian Foreign Minister Sergey V. Lavrov and the Russian ambassador to the United States, Sergey I. Kislyak, in a meeting that has generated furious controversy. "I hope that former Director Comey's testimony will help answer some of the questions that have arisen since Director Comey was so suddenly dismissed by the president", the top Democrat on the Senate Intelligence Committee, Mark Warner, said in a statement yesterday.
Earlier this week, investors dumped stocks in response to reports that Trump in February had asked Comey to stop investigating his former national security adviser, prompting accusations the president may have tried to hamper the probe. "He was insane, a real nut job", Mr. Trump said, according to the document, which was read to The New York Times by an American official.
The document was based on notes taken inside the Oval Office and the Times reports it has been circulated as the official account of the meeting.
President Donald Trump has hit out at the appointment of a special counsel to lead the Russian Federation probe as "the single greatest witch hunt" in U.S. history, hours after he said he looked forward to a thorough investigation. The White House has given different versions of the reasons for the dismissal. He says he thought that move was appropriate and produced a memo summarizing what he said were his "longstanding concerns" over Comey's handling of the Clinton email investigation.
"This is what OBSTRUCTION looks like: 'I faced great pressure because of Russian Federation".
Republican Representative Scott Taylor told CNN there was "no question" that Trump had "some stumbles this week".
The reports come as the President leaves for his first foreign trip.