Prime Minister Boris Johnson on Wednesday said he had full confidence that Britain and the EU will avoid a cliff-edge "no deal" at the end of this year, but refused to back down on controversial new legislation.

"It's not what this country wants (no deal) and it's not what our EU friends and partners want from us. Therefore I have every hope and expectation that that will not be the outcome," he told MPs.

However, Johnson said the European Union had "signally failed" to rule out a possible "blockade" between Britain and Northern Ireland if there is no deal, once a post-Brexit transition period ends on December 31.

"It's always possible that I'm mistaken and perhaps they will prove my suspicions wrong" in ongoing talks, he said. But otherwise, the unilateral new bill to regulate the UK's internal market was needed as an insurance policy.

"I prefer to have protections that guarantee the integrity of this country and protect against the potential rupture of the United Kingdom," Johnson said.

A "no deal" outcome would see tariffs imposed by both sides, and on Britain's side, they "would be quite formidable for some of their products", he added.