The UK's population will grow by more than the entire populations of Bulgaria, Latvia and Lithuania combined if the UK stays in the Single Market after Brexit, a think tank has warned.

A new analysis by Migration Watch found that unless free movement is curbed after Brexit, the UK's population will increase by more than 12 million people over the next 25 years, putting an ever increasing strain on public services.

It warned that the scope for a "significant reduction" in the level of migration is "extremely limited" if Britain remains a member of the single market and is subject to free movement rules.