“Even in the event that only a small majority of the British voters reject a withdrawal, we would have to see it as a wake-up call and a warning not to continue with business as usual.
“Either way, we have to take a serious look at reducing bureaucracy in Europe.”
The German politicians comments came as the Leave camp took a 19-point lead in the polls.
The Opinium Poll, commissioned by the Brexit-backing Bruges Gropu think tank, found 52 per cent are in favour of leaving the EU, while only 33 per cent want to remain.
A further 15 per cent still do not know but of those wanting to leave, 39 per cent said Britain should have some sort of free trade agreement with the EU, similar to the one currently enjoyed by the US, Canada and Mexico.