US president's top aide said Trump 'was dishonourable'

Donald Trump's chief of staff called the US president "dishonourable" over his firing of James Comey, the former FBI chief reportedly claims in his new book.

The president sacked Mr Comey in May, when he was heading an investigation into possible collusion between Russians and the Trump campaign during the 2016 election, saying he was "not able to effectively lead the bureau".

Mr Comey was in California on a work trip at the time and only learnt of his sacking when he saw the news break on television.

According to the Daily Beast news website, Mr Comey claims in his memoir that John Kelly, who was then head of the Department of Homeland Security, called him within minutes of his dismissal to offer his support.

Mr Comey writes that Mr Kelly, now the White House chief of staff, was "emotional" over the manner in which he was fired.

He went on to say that he "intended to quit" in protest because "he didn't want to work for dishonourable people", in a pointed reference to Mr Trump.

Mr Comey claims to have encouraged Mr Kelly, a retired general, to stay in post, telling him "this president", more than his predecessors, needed people of integrity around him.

Mr Kelly's offer to resign has previously been reported, but Mr Comey's comments offer the first confirmation of the story and reveal the fiery comments made by Mr Trump's right-hand man.

Mr Kelly is known to have a difficult relationship with the president but the revelations will likely cause further tensions in the West Wing.

It comes as the Republican Party launched a smear campaign against Mr Comey in anticipation of his tell-all book, which is expected to be heavily critical of Mr Trump. It takes the form of a website called "Lyin' Comey", which brands the former FBI chief as a discredited, partisan former official.

The extensive counter-offensive, funded by the Republican National Committee, also includes digital advertising to be sent to Republicans across the country before Mr Comey's book is published on Tuesday.

Meanwhile, Mr Trump's nomination for the new secretary of state, to replace the sacked Rex Tillerson, said he could imagine the US launching a ground invasion of North Korea.

Mike Pompeo said the US may at some point have to "move past diplomacy" to stop the regime's nuclear programme.

However, Mr Pompeo stressed he did not favour "regime change" and wanted to solve the world's crises with diplomatic rather than military means.