Theresa May and David Davis to push ahead with 'Great Repeal Bill' to end EU authority on day one of Brexit

The major announcement will be made on the first day of Conservative Conference in Birmingham

Brexit Secretary David Davis will tell the Tory Party faithful the change will mean ‘power and authority’ returned to the UK (EPA)

The Government will introduce a “Great Repeal Bill” to Parliament that aims to end the authority of European law in Britain from the very first moment the country has left the EU.

The historic proposal will scrap the European Communities Act, absorbing parts into UK law while giving ministers powers to ditch other elements they want rid of.

Prime Minister Theresa May and Brexit Secretary David Davis plan to introduce the Bill as early as the spring, with its passage through Parliament set to take place in parallel to withdrawal negotiations in Brussels.

The announcement is the centrepiece of the first day of Conservative Conference, with Mr Davis set to tell the party faithful the change will mean “power and authority” returned to the UK.

But it also sets the scene for a major clash in Parliament, as the Government will have to pass the Bill through a House of Lords where the Tories are in a minority and even some Conservative peers suggest they may try and delay Brexit legislation.

Ms May is expected to implement Article 50 of the Lisbon Treaty, formally triggering Brexit talks, early in 2017. That starts a two-year countdown in which a withdrawal deal must be struck before the UK departs the EU.

Mr Davis will say: "As we prepare for those negotiations in Europe, we also need to prepare for the impact of Brexit on domestic law. It’s very simple. At the moment we leave, Britain must be back in control. And that means EU law must cease to apply.

"To ensure continuity, we will take a simple approach. EU law will be transposed into domestic law, wherever practical, on exit day. It will be for elected politicians here to make the changes to reflect the outcome of our negotiation and our exit.

"That is what people voted for - power and authority residing once again with the sovereign institutions of our own country."

The Great Repeal Bill will, on day one of Brexit, end the authority of EU law by abolishing the 1972 European Communities Act - the legislation which means all law formed in Europe has primacy in the UK.

Currently if there is a clash between Parliament and EU law, the European Court of Justice decides on the matter and has in the past delivered judgments binding on the UK. The Government’s planned Bill will end ECJ jurisdiction in Britain.

At the same time, the new Bill will convert existing EU law into domestic law, while allowing Parliament to amend or repeal any other EU law after scrutiny and debate.

The Bill will also include powers for ministers to make some changes by secondary legislation, which is not voted on by the Commons in the same way a piece of primary legislation would be. Ministers already have such powers to implement parts of EU law. Officials say the powers are necessary to give the Government flexibility and to take account of the negotiations with the EU as they proceed.

But Mr Davis will dismiss any suggestion that ministers intend to use Brexit to ditch workers' right and in his speech will seek to highlight areas, including annual and parental leave, where UK law goes further than minimum EU standards.

He will say: "To those who are trying to frighten British workers, saying ‘when we leave, employment rights will be eroded’, I say firmly and unequivocally ‘no they won’t’.”