The European Union (EU) is set to approve a mandate on Monday for the European Commission (EC) to start negotiations for Britain's exit from the 27-member bloc.
It will also officially appoint former EU Commissioner Michel Barnier as the lead negotiator, Efe news reported.
The General Affairs Council ministers from the remaining countries will adopt a decision to authorise the opening of negotiations with London, as well as negotiating directives or mandate that will be given to EC, as an institution to conduct the talks, according to sources.
The two texts will be based on a recommendation presented on May 3 by the Commission and the guidelines adopted by the 27 state and government heads at an April 29 summit in Brussels.
The Council will also begin preparations for the summit scheduled to be held in June to discuss the progress of the negotiations, which according to the UK media will begin on June 19, only eleven days after elections in the country.
The directives adopted on Monday will guide the first phase of the negotiations and will refer to the citizens' rights, and the agreement over Brexit and the legal uncertainties surrounding it.
The EU wants to ensure its citizens continue to enjoy the same rights that UK citizens enjoy in the EU and also wants to bring in financial regulation to ensure London respects its obligations and commitments to the Community budget.
In order to ensure legal certainty, agreements must be concluded on all judicial proceedings pending in the EU Court of Justice on the date when the UK exits the bloc.
For issues that are not covered in this first phase, new directives will be adopted later, sources said.
The EU will be conducting step-by-step negotiations with London spread over phases, including a second phase that will determine its relationship with the UK, after it becomes a non-EU country.