A German official on Friday called for new sanctions against Russia over its role in the bombardment of Syria, saying Moscow's involvement in war crimes could not go unpunished.
Syrian government forces backed by Russian air power have stepped up an offensive on rebel-held parts of the city of Aleppo. Conflict monitors said hospitals had been hit and water supplies damaged in the most lethal bombardment in nearly six years of war.
Moscow and Damascus say they target only militants and deny they have bombed hospitals.
Norbert Roettgen, a member of Merkel's Christian Democratic Union (CDU) and chair of the Foreign Affairs Committee in the Bundestag, told the Sueddeutsche Zeitung that Russia's responsibility was beyond dispute.
"A lack of consequences and sanctions for the most serious war crimes would be a scandal," Roettgen said, adding military measures would be the wrong approach.
"Imposing economic sanctions wouldn't work in the short term, but in the long term they would certainly have some influence on (Vladimir) Putin's subsequent calculations," he added.
While some European lawmakers - including Elmar Brok, who is also a member of Merkel's CDU - have called for sanctions, a senior European diplomat has said sanctions could prove extremely difficult for Europe.
A German foreign ministry spokesman told reporters on Wednesday, shortly before Western officials met in Berlin to discuss the Syrian conflict, that there were no international proposals to impose sanctions on Russia over its role in Syria.
The EU has sanctions in place against Moscow over the conflict in Ukraine. Italy and some other EU states have said these should be eased, but the prospects for any relaxation of those sanctions had dimmed, given the crisis in Syria.
Roettgen criticised Europe for not clearly condemning Russia's involvement: "The least that Europe should do is use clear language which calls a war crime a war crime."
United Nations Secretary-General Ban Ki-moon said on Wednesday that those using "ever more destructive weapons" in Syria are committing war crimes and that the situation in the Syrian city of Aleppo is worse than a slaughterhouse.
For her part, German Chancellor Angela Merkel on Friday appealed to Russia to end what she called the "atrocious" violence in Aleppo, Syria, saying Moscow had a lot of influence on the Syrian government.
Merkel said there was no basis in international law for the bombing of hospitals, and Moscow should help end the escalating violence in the war-torn country.
REUTERS