Jeremy Hunt has warned Boris Johnson to keep his thoughts "private" amid a growing row over the UK’s post-Brexit customs arrangements.

The Health Secretary issued a direct rebuke to the Foreign Secretary and said the Cabinet must “work as a team” to give Theresa May the space she needed to deliver a “clean, decisive” Brexit.

Mr Hunt urged his Cabinet colleagues not to display “divisions in the open” because he believed the European Union “will exploit that” during negotiations.

Mr Johnson made headlines earlier this month after he described the Prime Minister’s preferred post-Brexit customs option as “crazy”.

Mr Hunt’s comments came as Damian Green, the former Cabinet minister and arch-Remainer, said he believed the UK would have to extend the post-Brexit transition period beyond the end of 2020.

Mr Green said a “bolt on” period may be needed to ensure that the UK’s new customs arrangements actually work.

He also suggested that Mrs May had backed the wrong option on customs - the customs partnership - as he said he believed a variation of the second option - known as maximum facilitation - was the “most likely endpoint”.

Downing Street rejected the idea of an extension to the transition period and said no deadline had been set for deciding which one of the options to adopt.