US national security adviser John Bolton is stepping down amid a dispute over whether he was sacked by the White House, or resigned.

President Donald Trump claimed on Twitter that he had fired Mr Bolton on Monday and told him his services were “no longer needed” following a series of disagreements between the pair.

However, Mr Bolton insisted that he had chosen to quit the post.

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President Trump and Mr Bolton had locked horns on a range of foreign policy areas, including Iran and Afghanistan.

Most recently Mr Bolton opposed the president’s now-scrapped plan to bring Taliban negotiators to Camp David.

....I asked John for his resignation, which was given to me this morning. I thank John very much for his service. I will be naming a new National Security Advisor next week. — Donald J. Trump (@realDonaldTrump) 10 September 2019

Tweeting earlier today, Mr Trump wrote: “I informed John Bolton last night that his services are no longer needed at the White House.

“I disagreed strongly with many of his suggestions, as did others in the Administration, and therefore I asked John for his resignation, which was given to me this morning.

“I thank John very much for his service. I will be naming a new National Security Advisor next week.”

Mr Bolton responded afterwards, posting on Twitter: “I offered to resign last night and President Trump said, ‘Let’s talk about it tomorrow’.”

I offered to resign last night and President Trump said, "Let's talk about it tomorrow." — John Bolton (@AmbJohnBolton) 10 September 2019

He also texted Washington Post reporter Robert Costa that "I will have my say in due course" and "my sole concern is US national security".

Fox News host Brian Kilmeade also said live on air that he received a text from Mr Bolton, which said: "Let's be clear, I resigned."

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Mr Bolton's came just hours before he was due to host a White House briefing with Secretary of State Mike Pompeo and Treasury Secretary Steven Mnuchin.

During a press conference, the pair were asked about whether the news had blind-sided them.

Mr Pompeo said: "I'm never surprised. And I don't mean that on just this issue.

"Those of us who work with the president have a good understanding of how he is thinking.

"Our mission is not to talk about the inner workings, but the things that matter to American foreign policy."

Mr Bolton was in London less than a month ago, where he met with Prime Minister Boris Johnson and said that the UK would be "first in line" for a trade deal with the US once Brexit has taken place.

Mr Bolton is seen as a hawk in foreign policy terms.

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He was a strong supporter of the 2003 Iraq war while serving in George W Bush's administration, and opposed President Trump's decision to hold back on military strikes against Iran.

He also warned against softening relations with North Korea and lobbied the president against the withdrawal of US troops from Syria.

Mr Bolton had a reputation as a warmonger, and Mr Trump once reportedly joked in an Oval Office meeting that "John has never seen a war he doesn't like".

However, relations had become increasingly strained between the pair - climaxing with row over inviting Taliban leaders to Camp David, which had been due to take place on Sunday.

Mr Bolton is the third national security adviser in the Trump administration, and the longest-serving to date.

He took over in April 2018 after the departure of General HR McMaster.