Philip Hammond's allies have accused Boris Johnson of being "simple minded" and warned that the Brexit transition period may need to be extended until after the next election.

Mr Johnson has made clear that a Brexit "implementation period" must last no longer than two years, meaning that the UK will effectively leave the EU by 2021.

However the Chancellor and other ministers including Amber Rudd, the Home Secretary, have argued that the UK will need at least an extra year so that businesses can adjust.

The deepening Cabinet split comes after Mrs May thought she had brokered a truce between Mr Hammond and Mr Johnson with a keynote speech in Florence on Friday.