US President Donald Trump has no intention of firing the special counsel investigating charges of possible Russian interference in the 2016 presidential election, even though he questioned the official’s impartiality in an interview, the White House says.

White House spokesman Sean Spicer has told a news briefing that while Mr Trump “retains the authority” to dismiss special counsel Robert Mueller, “he has no intention of doing that”.

Mr Trump voiced concern earlier on Friday (local time) about what he said was the close relationship between former FBI Director James Comey and Mr Mueller, who was named to take over the Russia investigation after Mr Comey was fired.

“He’s very, very good friends with Comey, which is bothersome,” Mr Trump told Fox News.

“We’re going to have to see. I mean, we’re going to have to see in terms — look, there has been no obstruction. There has been no collusion. There has been leaking by Comey.”

What is Mueller and Comey’s history?

Mr Mueller and Mr Comey served closely alongside each other in the Bush administration Justice Department, when Mr Comey was serving as acting attorney-general while Attorney-General John Ashcroft was in hospital.

They played pivotal roles in a 2004 White House confrontation, which began after Mr Comey refused to renew a sweeping domestic surveillance program.

In a dramatic 2007 testimony that helped cement his reputation for political independence, Mr Comey, who was the acting attorney-general at the time, recalled how he rushed to the hospital to prevent White House officials from trying to coax Attorney-General John Ashcroft into reauthorising the program.

He called his chief of staff and told him to get as many people to the hospital as possible.

“I hung up, called Director Mueller — with whom I’d been discussing this particular matter and had been a great help to me over that week — and told him what was happening,” Mr Comey testified.

“He said, ‘I’ll meet you at the hospital right now.'”

Mr Mueller instructed his agents not to allow Mr Comey to be removed from Mr Ashcroft’s room and showed up as promised at the hospital.

Mr Comey was prepared to resign from the Justice Department if his concerns were ignored and, he said, Mr Mueller was among the officials willing to leave, too.

What have they said about each other?

Though they were allies that dramatic night, another takeaway to their supporters is a shared commitment to the rule of law.

The former FBI directors have spoken warmly of each other over the years, with Mr Comey describing Mr Mueller at 2007 hearing as “one of the finest people I’ve ever met”.

And when Mr Comey was selected by President Barack Obama in 2013 to succeed Mueller as FBI director, the former White House director praised Mr Comey as a man of “honesty, dedication and integrity” at a White House ceremony.

Mr Comey repaid the favour minutes later by joking that he “must be out of my mind to be following Bob Mueller”.

So, are they close?

They are not known to be especially close friends, and legal experts say whatever connection they do have does not come close to meriting Mr Mueller’s removal.

David Kelley, who succeeded Mr Comey as US attorney in Manhattan and has known him and Mr Mueller for years, said the pair have not been to each other’s houses.

“Jim has never been to Bob’s house. Bob has never been to Jim’s house,” he said.

“They’ve had lunch together once and dinner together twice, once with their spouses and again after Jim became the FBI director so that Bob could give him the rundown of what to look for.”