The top United Nations human rights official said the situation in Syria was reminiscent of Bosnia's sectarian war and called on world powers on Thursday to unite in trying to halt the bloodshed.
"The memories of what happened in Bosnia and Herzegovina should be sufficiently fresh to warn us all of the danger of allowing Syria to descend into an all-out sectarian conflict," UN High Commissioner for Human Rights Navi Pillay said.
"It should not take something as drastic as Srebrenica to shake the world into taking serious action to stop this type of conflict," she told reporters.
The July 1995 massacre in Srebrenica was the worst on European soil since World War Two. Dutch UN peacekeepers abandoned what had been designated a UN safe haven to advancing Bosnian Serb forces who then killed 8,000 Muslim men and boys and bulldozed their corpses into pits.
Pillay, a former UN war crimes judge, said both sides in the Syrian conflict may have committed war crimes or crimes against humanity.
"The indiscriminate use of heavy weaponry by government forces to destroy large swathes of cities such as Homs and Aleppo is inexcusable, as is the use of huge bombs by extremist opposition groups which kill and maim civilians as well as military targets," she added.
Meanwhile on Thursday, Syrian activists said that a string of government airstrikes on rebel areas in the country's north has killed at least 20 people, leveled buildings and forced residents to dig through mounds of rubble in search of survivors.
The activists said the strikes happened late Wednesday and early Thursday and hit a total of four towns in Idlib and Aleppo provinces.
They said residents are searching through the rubble in some of the towns, while in others the dead were buried before being identified.
Videos of the strikes posted online show leveled buildings and survivors pulling bodies from the debris.
Activist claims and videos could not be independently verified.
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