Prime Minister Theresa May is to talk to European Union leaders about continuing UK involvement in the European Arrest Warrant and the EU police force after Brexit, once she triggers Article 50 on Wednesday.

Attention has focused on the UK’s future trade relationship with the EU but Mrs May, a former Home Secretary, said continued co-operation to fight crime and terrorism was also important.

She was speaking to the Birmingham Mail during a visit to Birmingham, in which she attended the UK-Qatar Business and Investment Forum at Birmingham’s ICC and met Andy Street, the Conservative candidate in the election for a West Midlands mayor on May 4.

The European Arrest Warrant is a warrant valid throughout all member states of the European Union. Once issued, it requires any member state to arrest and transfer a criminal suspect.

And Mrs May also suggested she would talk about continued UK involvement in Europol, the EU’s law enforcement agency.

She said: “The important thing is that although a lot of the discussion is about the trade agreement we will be negotiating with the EU, there will be other elements to our negotiations.

“The whole question of co-operation on security and justice and home affairs will be part of that as well.

“There will be issues like the European Arrest Warrant, like access to Europol. These are all aspects of that security and justice and home affairs area that will be part of the negotiations which will start once we’ve triggered [Article 50] and once the EU council have set their guidelines”.

Prime Minister Theresa May speaking to the Birmingham Mail's Political Editor Jonathan Walker

The Prime Minister set out the process of triggering Article 50.

She said: “The actual process of triggering is simply I send a letter to President Tusk, as President of the EU Council, invoking Article 50 (2), which enables us to say that we want to leave the European Union. And that will be handed to him.

“I will make a statement in Parliament.”

Reports have suggested the letter could be six pages long. Asked about this, she said: “Some people think it should be one page long. Some people think it should be 20 pages long.”

The European Council, led by Mr Tusk, will meet on April 29 and agree guidelines which will then be sent to the EU Commission, setting out how negotiations are to be conducted.

Carmakers such as Nissan have stressed the need for continued access to the EU single market, not only so that they can sell vehicles in EU countries but also so that they can import parts from EU suppliers without delays.

Mrs May said she understood the need for “frictionless” trade.

She said: “I want to see, if you talk to businesses of all sorts across the country, they value the ability to trade in goods and services as seamlessly and frictionlessly across borders into the European Union.

“We want a comprehensive free trade agreement with Europe that enables us to have as free and frictionless as possible trade in goods and services with the European Union remaining member states.”