The German leader, who cut short her summer holiday to speak after a string of Islamist attacks rocked the country, said the entire continent was being "ravaged" by terrorism.

She described recent attacks in Ansbach, Wurzburg and Munich as "horrifying and depressing" but insisted Germany would not turn its back on people fleeing the Middle East. 

In the wake of the killings, Mrs Merkel said Germany now needed a better "early warning system" to spot radicalised Muslims among the newly-arrived migrants.

She said the central government would "redouble its efforts" against the threat, increasing staff numbers and resources for security services.