One immigration pressure group estimates 50, 000 people will move to the UK every year from Romania and Bulgaria once the movement restrictions expire at the end of the year, but Mr Hague said any attempt to estimate the number would be "guesswork".

BBC: No 10 considering curbs to tackle 'benefit tourism'

We assess that the underlying factors fueling the spread of the movement outweigh its vulnerabilities and are likely to do so for the duration of the timeframe of this Estimate.

NPR: Both Parties Find Ammo in Threat Summary