Media playback is unsupported on your device Media caption President Donald Trump seeks to set the record straight

US President Donald Trump has insisted he is not under investigation, while dismissing the FBI director he fired as a "showboat" and "grandstander".

Mr Trump also told NBC News it was his decision alone to sack James Comey.

Mr Comey was leading an inquiry into alleged Russian meddling in the US election and possible collusion between Trump campaign officials and Moscow.

Mr Trump has dismissed the probe as a "charade", a claim directly contradicted by Mr Comey's successor.

In his first interview since firing the FBI director, Mr Trump told NBC News on Thursday he had asked Mr Comey whether he was under investigation.

"I said, if it's possible would you let me know, 'Am I under investigation?' He said: 'You are not under investigation.'"

Media playback is unsupported on your device Media caption What do Trump supporters think about Comey's firing?

"I know I'm not under investigation," Mr Trump told the interviewer, repeating a claim he made in Tuesday's letter of dismissal to Mr Comey.

Trump's dinner description challenged

President Trump said Mr Comey first told him this at a dinner at the White House, which the FBI chief had requested because "he wanted to stay on" in his post under the new administration.

But NBC later quoted an unnamed former senior FBI official close to Mr Comey as saying it was the White House that had requested the dinner, and that Mr Comey would not have told the president he was not under investigation.

"He would say, 'look sir, I really can't get into it, and you don't want me to'," the former official was quoted as saying.

The White House has rejected concerns raised by legal experts that the conversation, as described by Trump, may have been improper.

Spokeswoman Sarah Huckabee Sanders said she "did not see it as a conflict of interest".

According to the New York Times, two people who had heard Mr Comey's account - apparently of the same dinner - said Mr Comey declined a request to pledge loyalty to Mr Trump, but said he would be honest with him.

How the sacking narrative has changed

The president also appeared to undercut the initial White House explanation that he had fired Mr Comey on the recommendation of top justice officials.

"He's a showboat. He's a grandstander. The FBI has been in turmoil. I was going to fire Comey. My decision," Mr Trump said.

White House officials had previously pinned the decision on a memo written by Deputy Attorney General Rod Rosenstein, which Mr Trump refers to in the opening paragraph of his termination letter to Mr Comey, saying, "I have accepted their recommendation".

But he told NBC: "I was going to fire him regardless of the recommendation."

White House firefighting - Anthony Zurcher, BBC North America reporter

On Thursday afternoon, the president took a wrecking ball to the White House's days of work.

Oftentimes, it seems like the president and his press office are operating from different playbooks.

The president says or tweets what he chooses, and his staff scrambles to explain the context or douse the flames of controversy.

It happened when the president boasted about the size of his inauguration crowd, alleged that there were millions of illegal votes in the presidential election and accused Barack Obama of "wiretapping" him, among many other instances.

On Thursday afternoon it was time to bring out the brooms once again.

Read more from Anthony Zurcher: Three takeaways from the NBC interview

Inquiry should be 'so strong'

Mr Trump also denied that he wanted the FBI inquiry on Russia dropped, saying he, instead, wanted it "speeded up".

"I want to find out if there was a problem with the election having to do with Russia... or any other country, I want that to be so strong and so good, and I want it to happen."

This is despite saying in a tweet on Monday: "The Russia-Trump collusion story is a total hoax, when will this taxpayer funded charade end?"

"There's no collusion between me and my campaign and the Russians," he told NBC.

Media playback is unsupported on your device Media caption Trump's love-hate relationship with Comey over a tumultuous year

Mr Trump said he had just sent a letter via a law firm to Republican Senator Lindsey Graham stating that he has no stake in Russia.

"I have nothing to do with Russia," he said. "I have no investments in Russia. I don't have property in Russia. I'm not involved with Russia."

What did the new acting FBI chief say?

The White House has depicted the Russia inquiry as "probably one of the smallest things" that the FBI has "got going on their plate".

But acting FBI Director Andrew McCabe said on Thursday that it was "a highly significant investigation".

In testimony to the Senate intelligence committee, he also cast doubt on White House claims that Mr Comey had lost the confidence of his staff.

Media playback is unsupported on your device Media caption Donald Trump was with Henry Kissinger when he told reporters James Comey was "not doing a good job" as FBI chief

"I can confidently tell you that the vast majority of employees enjoyed a deep and positive connection to Director Comey," Mr McCabe said.

The acting FBI director vowed not to update the White House on the status of the investigation and to notify the Senate panel of any attempt to interfere with the inquiry.

Republican committee chairman Richard Burr asked Mr McCabe if he had ever heard Mr Comey tell Mr Trump the president was not the subject of investigation.

Image copyright Getty Images Image caption Andrew McCabe said the FBI had full faith in James Comey

Mr McCabe said he could not comment on an ongoing inquiry.

The acting FBI director did not confirm reports that Mr Comey had asked for more resources for the agency's Russia inquiry.

Mr McCabe said he believed the FBI had sufficient funding to conduct the probe.