LONDON - British Prime Minister Theresa May has not ruled out allowing the free movement of people between Britain and the European Union during "an implementation phase" after Britain leaves the bloc, the BBC reported on Wednesday.

May, who triggered the formal divorce procedure with the EU last week, has said she expects some kind of implementation phase, or transitional agreement, after two years of talks with the bloc.

She has offered few details on how an implementation phase would operate, but if Britain wants to keep the status quo before finalizing a deal, it will have to accept the EU's rules - the so-called four freedoms allowing the free movement of people, capital, goods and services.

Asked whether her government would rule out the free movement of people in any transitional period after the terms of Britain's departure from the EU were agreed, May declined to do so, the BBC said.

"Once we've agreed what the new relationship will be for the future, it will be necessary for there to be a period of time when businesses and governments are adjusting systems and so forth," May told reporters on a visit to Saudi Arabia.

A major reason

Concern over immigration from the EU was a major reason behind Britain's vote to leave and May has said she will respect those fears by not seeking membership of Europe's single market which would mean allowing freedom of movement of people.

She added that Britain would have "control of our borders and control of our immigration", the BBC reported.

Citing the same conversation with reporters, the Financial Times said May had suggested that Britain would not be able to complete a new trade deal with the EU until after Brexit happens in 2019, saying that there was a "legal situation in terms of how the European Union can conduct trade negotiations".

However May said that by the time Britain leaves the EU, "it's right that everybody should know what the future arrangements, the future relationship, that future partnership between us and the EU will be".

The European Parliament was scheduled to lay down its "red lines" for negotiations on Wednesday over a Brexit deal, on which the assembly will have the final say in two years' time.

The parliament in Strasbourg, France, was set to back a call by EU leaders for Britain to first agree to divorce terms before striking any new trade deal with the bloc.

"We want to have a clear signal that the European Union is united," said German MEP Manfred Weber, the head of the conservative European People's Party, the parliament's biggest bloc.