White House national security adviser John Bolton has resigned at the request of President Donald Trump, who said he called for the resignation due to numerous policy disagreements.

Mr Trump says he sacked the chief adviser on Monday but Mr Bolton has given an alternative take on his sudden and surprising departure.

The president’s third national security adviser claims he quit on Monday but Mr Trump suggested the pair instead “talk about it [on Tuesday]”.

Tweet from @AmbJohnBolton

The opposing accounts on Mr Bolton’s less-than-friendly departure is yet another example of what had been a fractious relationship almost from the start.

Both men routinely had significant disagreements on Iran, Afghanistan and a raft of other global challenges.

Democratic Senator Chris Murphy said Mr Bolton’s abrupt exit was a cause for worry.

“I’m legitimately shaken by the grave instability of American foreign policy today,” Mr Murphy tweeted.

“I’m no Bolton fan, but the world is coming apart, and the revolving door of US leadership is disappearing America from the world just at the moment where a stable American hand is most needed.”

Tweet from @realDonaldTrump

Tensions coming to a head

In recent months, tensions have risen between Mr Bolton and US Secretary of State Mike Pompeo over influence in the president’s orbit and how to manage the president’s desire to negotiate with some of the world’s most unsavoury actors.

Mr Bolton has remained sceptical about the president’s whirlwind rapprochement with North Korea, and advocated against the decision last year to pull US troops out of Syria.

He masterminded a quiet campaign inside the administration and with allies abroad to persuade Mr Trump to keep US forces in Syria to counter the remnants of the Islamic State and Iranian influence in the region.

Mr Bolton was also opposed to Mr Trump’s now-scrapped notion to bring Taliban negotiators to Camp David last weekend to try to finalise a peace deal in Afghanistan.

South Carolina Senator Lindsey Graham, who was travelling with Mr Trump Monday, said reports of Mr Bolton’s dissent on the Taliban meeting were a “bridge too far” for the President.

One Republican familiar with the disagreements between Mr Trump and Mr Bolton said the adviser’s opposition to a possible meeting between Trump and Iranian President Hassan Rouhani was a precipitating factor in the dismissal.

Mr Bolton’s ouster came as a surprise to many in the White House.

Just an hour before Mr Trump’s tweet, the press office announced that Bolton would join Mr Pompeo and Treasury Secretary Steven Mnuchin in a briefing.

White House spokesman Hogan Gidley said Charles Kupperman, the deputy national security adviser and a former Reagan administration official and defence contracting executive, would fill Bolton’s role on an acting basis.

Mr Trump said he would name a replacement for Mr Bolton next week. Mr Bolton was named the president’s third national security adviser in March 2018 after the departure of Army General HR McMaster.

– With AAP