LONDON (Reuters) - Former British foreign minister Boris Johnson called again on Sunday for Prime Minister Theresa May to change course on Brexit, accusing her of forcing through a deal to keep the country locked in the EU’s customs union in a “total surrender”.

Conservative MP Boris Johnson walks through his garden at his home near Oxford, Britain, October 3, 2018. REUTERS/Toby Melville

It was the latest call by Johnson, the figurehead of Britain’s campaign to leave the European Union, for May to drop her so-called Chequers plans in favor of negotiating a clean break with the bloc and securing a Canada-style free trade deal.

His comments come days after his brother, fellow Conservative lawmaker Jo Johnson, resigned as a transport minister over Brexit. Boris Johnson said he agreed with his brother that the Brexit talks were “the biggest failure of UK statecraft since Suez” when Britain lost control of the waterway in the 1950s.

“I really can’t believe it but this government seems to be on the verge of total surrender,” he wrote in his weekly column in the Telegraph newspaper.

“I want you to savor the full horror of this capitulation ... we are on the verge of signing up for something even worse than the current constitutional position. These are the terms that might be enforced on a colony.”

The Independent website reported that May has been forced to abandon plans for a cabinet meeting on Monday to approve a Brexit deal.

Johnson accused the government of being unable to negotiate a way to end unilaterally a so-called backstop arrangement, designed to prevent the return of border controls between the British province of Northern Ireland and EU member Ireland.

Such a failure would turn Britain into “a vassal state” until the bloc decided to move on to trade talks, he said.

“It is frankly hard to see why they should,” he wrote, adding that May’s Chequers plans, named after her country residence, were very much alive despite widespread criticism.

“The essence of the idea - that the UK should remain in the customs union and the single market for goods and agri-food - is what the backstop entails. And you can be absolutely sure that this idea will be at the heart of the ‘deal’ that I have no doubt the prime minister will shortly and magically secure.”