Another prerequisite to expansion is the extension of qualified majority voting (QMV) in the European Council.

BBC: Europe: The issues

It would expand the policy areas subject to qualified majority voting (QMV), rather than unanimity.

BBC: Irish EU treaty referendum closes

The areas presently subject to QMV are limited, with key issues requiring agreement by all EU members.

BBC: Europe: The issues

But extending QMV is a highly sensitive domestic issue for most members.

BBC: Europe: The issues

The argument about City regulations was about the danger of a newly united eurozone being able to outvote the UK - using qualified majority voting or QMV - under new rules which are still due to come in 2014.

BBC: Europe - the coalition shakes