“What is happening there amounts to what is the worst in the world,” said Mahmoud Almizeh, a 19-year-old Syrian refugee who comes from Raqa, now the bastion of the Islamic State jihadist group. Germany has opened its doors to some 600,000 Syrian refugees since the conflict began in 2011.

 Having arrived in Germany a year ago, Almizeh lamented that European leaders were “unfortunately doing nothing”.

 In Aleppo on Saturday trapped Syrian civilians and rebels waited desperately for evacuations to resume from an opposition-held enclave of the city which has fallen to the brutal onslaught by Syrian government forces. Aleppo has been ravaged by some of the worst violence of the nearly six-year war that has killed more than 310,000 people.