US Secretary of State

Powell, a retired four-star general who served as chairman of the joint chiefs of staff in the early 1990s, had been treated for Covid at Walter Reed national medical center in Bethesda, Maryland, where he died. He was fully vaccinated against coronavirus but had a compromised immune system having been treated for blood cancer.

Announcing his death, his family said they had lost a “remarkable and loving husband, father, grandfather and a great American”.

He pointedly failed to thank Mr Trump or praise his policies.

The former ExxonMobil chief had a series of public rifts with the White House after being appointed last year.

Mr Trump officially fired Mr Tillerson via Twitter, naming CIA Director Mike Pompeo as his replacement.

Mr Trump also named Gina Haspel to become the CIA's first female director.

Speaking to reporters at the Department of State, Mr Tillerson said good work had been done to have better relations with China, and rein in North Korea's nuclear weapons programme.

Russia had agreed to ensure Syria's chemical weapons stockpiles were destroyed - and its failure to do this enabled the attack, he said.

G7 foreign ministers are preparing to meet in Italy later on Monday.

Talks will focus on how to increase pressure on Russia to distance itself from Syria's President Bashar Al-Assad.

On Tuesday, Mr Tillerson will continue from the G7 to Moscow, where he will meet his Russian counterpart, Sergei Lavrov.

Russia is the Syrian government's main ally, and helped facilitate a 2013 agreement to destroy Syria's chemical arsenal.

Mr Tillerson outlined the tougher strategy to confront North Korea's nuclear threat while visiting South Korea on his three-country tour of Asia.

He also closed the door on talks with Pyongyang unless it denuclearised and gave up its weapons of mass destruction.

When asked about the possibility of using military force, Mr Tillerson told a news conference in the South Korean capital: "All of the options are on the table".