Donald Trump has decided to sack National Security Advisor H R McMaster after complaining that his intelligence briefings are too long, according to reports.

The US President, who fired Secretary of State Rex Tillerson on Tuesday, is already said to be considering replacements for the three-star Army general.

The move was reported by the Washington Post just hours after General McMaster blamed Russia for the nerve agent attack in Salisbury and accused them of complicity in Syrian atrocities.

General McMaster was appointed in February last year following the resignation of Michael Flynn, who has since pleaded guilty to lying to the FBI about his contacts with the Russian government.

According to the Post, Mr Trump has 'never personally gelled' with Gen McMaster but wants to take time before announcing his departure.

He has "complained that McMaster is too rigid and that his briefings go on too long and seem irrelevant", it said.

On Thursday, Gen McMaster pointed the finger at Russia for "the abhorrent nerve agent attack" on former spy Sergei Skripal in Salisbury.

"We believe that Russia was responsible for this attack and we call on the Russian government to answer all questions related to this incident," he said.

He also suggested Russia was complicit in atrocities by Syrian President Bashar al-Assad's regime and called for "serious economic and political consequences".

Mr Trump is said to be considering replacing the general with the former ambassador to the UN, John Bolton, or Keith Kellogg, chief of staff of the National Security Council.

White House Chief of Staff John Kelly - who has himself been the subject of departure rumours - is said to be "eager to see McMaster go".

The report was rejected by White House press secretary Sarah Huckabbee Sanders, who said Mr Trump and General McMaster 'have a good working relationship'.

General McMaster's departure would be the latest in a string of high-profile sackings and resignations since the start of the year, including the President's economic adviser Gary Cohn and communications director Hope Hicks.

The President reportedly feels "emboldened" after his decisions to agree to meet with Korean leader Kim Jong-un and to impose tariffs on steel and aluminium.

After sacking Mr Tillerson on Tuesday, he told reporters: "I'm really at a point where we're getting very close to having the Cabinet and other things that I want."

Mr Trump is expected to make CIA director Mike Pompeo his new Secretary of State and has announced that conservative TV pundit Larry Kudlow will be the next head of the White House National Economic Council.

The President has indicated that the revolving door at the White House will keep on turning, telling reporters: 'There will always be change.'