The former foreign secretary told Theresa May in his resignation letter that the Brexit “dream is dying”.
He said: “Brexit should be about opportunity and hope. It should be a chance to do things differently. To be more nimble and dynamic and to maximise the particular advantages of the UK as an open, outward-looking, global economy.
“That dream is dying, suffocated by needless self-doubt.”
Mr Johnson claimed that the UK has ended up postponing “crucial decisions” such as preparing for a no-deal Brexit.
He warned that, as a result, the country risks heading for a “semi-Brexit” which will leave chunks of the UK economy locked within the trading bloc – without the country having any control.