German Chancellor Angela Merkel on Friday demanded an end to attacks by Syrian government forces and Russia on the northern city of Aleppo, adding that the European Union would take measures against both if the "barbaric" campaign continued.

"We demand an end to the attacks. We have not only said that we could not only impose sanctions against Syria but also sanctions against all who are allied with Syria. This applies to Russia," Merkel said in Brussels.

EU leaders condemned Russia for its bombing of civilians in the besieged city of Aleppo but faced resistance from Italy to impose new sanctions against Moscow over the atrocities.