"This agreement in principle is magnificent news. Now we only hope that the British parliament will approve it, to turn it into a definitive agreement," Marcelo Rebelo de Sousa told journalists on the balcony of the Belém Palace in Lisbon.

According to the head of state, its approval by the British parliament "would be enormous news for Europe and enormous news for the United Kingdom, insofar as it occurs before 31 October, insofar as it avoids what would be a much more serious situation, that of leaving without agreement".

"And to the extent that it shows, on the part of the European Union, as of the United Kingdom, at government level, a willingness to work until the end to have an understanding, thinking of millions and millions of citizens. So let us hope now that on Saturday the British parliament can approve the agreement," he added.

The Portuguese Prime Minister, António Costa, also welcomed today, in Brussels, the agreement announced by the Prime Minister of the United Kingdom, Boris Johnson, and by the President of the European Commission, Jean-Claude Juncker, considering it "excellent", but recalled that the British Parliament has already failed other commitments and said it hopes that "the fourth will be for good".

This agreement for Britain's withdrawal from the European Union - decided by British citizens in a referendum held on 23 June 2016 - was announced a few hours before the start of a European Council that will start precisely with a discussion of this commitment.

The final text of the agreement has to be validated by the Heads of State and Government meeting at the European Council between today and Friday and ratified by the UK Parliament and the European Parliament.

According to the European Union's chief negotiator for Brexit, Michel Barnier, Brussels and London have reached "a fair and reasonable basis" for the UK to leave the European Union in an orderly fashion and to start "as soon as possible a new partnership".

"There is no surprise, much of this final text is in the agreement that we proposed almost a year ago. There are just a few new elements, particularly on Ireland and Northern Ireland, and in the political declaration," said Barnier in the European Commission's conference room, presenting the new commitment for Brexit, which is due to take place on 31 October.