Citizens of the United Kingdom may not retain the fundamental rights and freedoms of the European Union following Brexit, according to a report presented Tuesday to the European Parliament.

Two EU law experts, Spaniards Antonio Fernández Tomás and Diego López Garrido, told the EP that key EU ideals such as the free movement of persons, goods, workers and the right of establishment will no longer apply to Britons once the UK pulls out of the bloc.

The two professors, employed at the University of Castilla-La Mancha, said there are no acquired rights attached to EU membership, meaning that UK citizens will not have any automatic protections once Brexit is fully enacted.

On the contrary, Tomás and Garrido said, their future rights will depend on London and Brussels using the two-year negotiating period to strike an adequate compromise over residency and other essential matters.

The study, titled "The impact and consequences of Brexit on UK and EU citizens," had been commissioned by the EP's Policy Department for Citizens' Rights and Constitutional Affairs.

Tomás said during his presentation that, historically, there were no legal precedents for individuals maintaining their rights after a change in the prevailing legal order, except perhaps in the case of the right to private property.

He added that "there is no objection to implementing a transitional period where the UK and the EU could agree to extend those rights."

Meanwhile, Garrido stressed the importance of a broad pact that would put an end to uncertainties looming over UK citizens living in the EU as to which of their rights could disappear after Brexit.

He said that there should be three main agreements between Brussels and London: a withdrawal agreement (triggered by Article 50), a transitional period agreement and a post-Brexit agreement in which the UK is considered a non-member state.

Garrido added that the status of citizens' fundamental rights should be carefully determined in the first agreement to avoid using individual freedoms as bargaining chips during negotiations.

"Two years seems a long time to those citizens to know what's going to happen in their future," he concluded. "That's why we're saying we need to look at citizens' rights first and foremost, that is the most urgent issue."

The final Brexit deal will be subject to the EP's approval.