“The question that arises after Cologne is when do you lose your right to stay with us?” said Mrs Merkel. “I have to say that, for me, we must take it away sooner. We must do this for us – and for the many refugees who were not part of the events in Cologne. I think there are indications that changes must happen.”

Mrs Merkel added: “The interior minister and the justice minister are discussing just what we could improve.”

But Mrs Merkel refused to retreat from her open-door policy for refugees, which saw 1.1 million people arrive in Germany in 2015 alone. Whether it would be legally or practically possible to deport an offender back to Syria – where a civil war is raging – remains unclear.

Nor is it clear whether any reforms would apply retrospectively to those who committed offences in Cologne on New Year’s Eve.