U.N. Alarmed at Syria 'Atrocities', Fears for Aleppo

The U.N. human rights chief voiced alarm Friday at reports of atrocities in Syria and warned that civilians were at "grave risk" amid fears of a major battle in the second city of Aleppo.

"I have been receiving as yet unconfirmed reports of atrocities, including extra-judicial killings and shootings of civilians by snipers, that took place during the recent fighting in various suburbs of Damascus," U.N. High Commissioner for Human Rights Navi Pillay said in a statement.

"It goes without saying that the increasing use of heavy weapons, tanks, attack helicopters and -- reportedly -- even jet fighters in urban areas has already caused many civilian casualties and is putting many more at grave risk.

"All this, taken along with the reported build-up of forces in and around Aleppo, bodes ill for the people of that city," she said.

Attacks were also taking place in other towns including Homs and Deir al-Zour with "devastating consequences", she said, adding that a "discernible pattern has emerged" in the way government forces clear areas they claim are occupied by the opposition.

Typically, villages are surrounded before water, electricity and food supplies are cut. "Intense shelling and bombardment" then follow, "with air support from attack helicopters, and now reportedly even jet aircraft".

Tanks then advance on the towns, "followed by ground forces who proceed door-to-door and reportedly often summarily execute people they suspect of being opposition fighters", she said.

Sometimes the bodies of those executed are burned or taken away.

Pillay said she received increasing reports of opposition fighters torturing or executing prisoners and that those who are committing such crimes "should not believe that they will escape justice".

"The world does not forget or forgive crimes like these," she added.

Between one million and 1.5 million people have fled their homes since the conflict began, according to the Office of the High Commissioner for Human Rights (OCHCR).

Opposition activists say the conflict has killed more than 19,000 people since March 2011.