European leaders could change immigration rules to stop Britain leaving the European Union next year, Tony Blair has said.

The former Prime Minister said immigration is the "number one issue" for many people on the Continent.

Mr Blair - who makes a speech on the EU in Brussels today - said that he was not offering the chance to renegotiate Britain's terms of its EU membership "on a whim".

He said: "People will not get rid of freedom of movement principle - and neither should they because that is to the advantage of the European Union.

"But I was talking to a Belgian politician here in Brussels yesterday who explained to me all the things that Belgium do in order to restrict European immigration to the very specific circumstances allowed by freedom of movement and not more than that.

"The truth is that there are many things that Britain could do even within the existing system to tighten it if we wanted to prioritise tightening immigration over bringing people in to do tasks in the British economy.

"There are changes that Europe would make to its own external border system as well - there is a big debate going on about that now because they realise they have got huge problems with their borders."