Parliament will not be able thwart Brexit by using a vote expected later this year on the final deal negotiated with the European Union to overturn the result of the 2016 referendum, Brexit minister David Davis said on Tuesday.

With just over a year left until Britain is due to leave the EU, opponents of Brexit are exploring ways to stop what they call Britain's biggest mistake since World War Two.

They have identified winning enough support in the lower house of parliament, the House of Commons, to block any possible deal the government brings back from Brussels as their best chance of overturning Brexit.

But Davis told a committee of lawmakers: "I don't view a meaningful vote as overruling the referendum if that's what you mean."

British supporters of the EU say a defeat in parliament could prompt a political crisis, topple Prime Minister Theresa May, lead to a general election and a second referendum.

Former British Prime Minister John Major said last week the vote in parliament is of such national importance that politicians should vote according to their consciences, not on party lines, and that a defeat could to lead to a second vote on EU membership.

Davis also said the government would not stop planning for a no-deal Brexit scenario even if agreement on a transitional period is reached with the EU later this month.

"It's always possible, it's highly improbable but always possible that the deal will come apart at the end for some wholly unpredictable reason," Davis said. "A responsible government has to be ready for that outcome."