Elon Musk has posted a string of scathing social media comments, hitting out at Donald Trump’s counsellor for trade, Peter Navarro. The Tesla founder and CEO accused Mr Navarro of being “dumber than a sack of bricks”, as the tariff policy unveiled by the US President last Wednesday has seemingly sparked a divide between the Trump administration and Mr Musk.

The Tesla founder labelled Mr Trump’s adviser a “moron” during a deepening row which had seen Mr Navarro accusing the billionaire of being a “car assembler” rather than a manufacturer. Hitting back at claims of the X owner wanting to use “cheap foreign parts”, Mr Musk insisted his company “has the most American-made cars”. President Trump is already facing mourning pressure from countries worldwide after his retaliatory tariffs prompted panic and stock markets to crash.

Speaking to CNBC, Mr Navarro hit out at Tesla for allegedly using foreign car parts, saying: “In many cases, if you go to his Texas plant, a good part of the engines that he gets – which in the EV case are the batteries – come from Japan and come from China. The electronics come from Taiwan.”

Taking to his social media platform, Mr Musk responded: “Tesla has the most American-made cars. Navarro is dumber than a sack of bricks.”

He added: “By any definition whatsoever, Tesla is the most vertically integrated auto manufacturer in America with the highest percentage of US content. Navarro should ask the fake expert he invented, Ron Vara.”

The tech tycoon referenced the criticism that Mr Trump’s adviser faced this week for inventing Ron Vara, a made-up source in his books, whose name is an anagram of his own.

The latest spat follows Mr Musk’s comments via video-link at a congress in Florence of Italy's right-wing, co-ruling League Party.

He said: "At the end of the day, I hope it's agreed that both Europe and the United States should move ideally, in my view, to a zero tariff situation, effectively creating a free trade zone between Europe and North America.

In a comment that could be perceived as a criticism of Mr Trump's leading policy on tariffs, Mr Musk added: "If people wish to work in Europe or wish to work in North America, they should be allowed to do so in my view." He also noted it "has certainly been my advice to the president".