One of the EU’s founding principles is the free movement of people (along with the free movement of goods, services and money).
Because of this, the UK has no control over immigration from other EU member states.
Brexiters often cite health and benefits tourism from other EU citizens – where people visit or migrate to the UK because of what they perceive as a more generous welfare system, or the NHS.
The issue of how to regulate welfare for EU migrants was one of the main sticking points in David Cameron’s recent negotiations with EU leaders.
Recently, some pro-Brexit ministers have claimed the UK is at greater risk of a terror attack while part of the EU.