About 51,000 people have been displaced since Damascus, backed by Russian air strikes, launched its latest offensive on the Syrian city of Aleppo last week, the United Nations reported Thursday.
"Since the latest offensive by Government forces began last week in the Governorate of Aleppo, reportedly accompanied by numerous air strikes by Russian and Syrian aircraft, some 51,000 civilians have been displaced and a further 300,000 are at risk of being placed under siege," UN human rights chief Zeid Ra'ad Al Hussein said in a statement.
President Bashar Al-Assad's forces backed by Russian warplanes have since February 1 captured a string of villages around opposition-held Aleppo and managed to cut a major rebel supply route to the city.
The air strikes have been blamed for derailing UN-backed talks in Geneva aimed at ending Syria's tangled, nearly five-year conflict and for threatening Europe with another huge influx of refugees.
Zeid said Thursday that "dozens of civilians" had reportedly been killed in the attacks.
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The Syrian Observatory for Human Rights has estimated that at least 500 people have been killed since the offensive on Aleppo began.
Zeid voiced "utmost alarm" at the rapidly worsening human rights situation in and around Aleppo and elsewhere in Syria, where he said "shocking violations and abuses are committed on a daily basis."
"The warring parties in Syria are constantly sinking to new depths, without apparently caring in the slightest about the death and destruction they are wreaking across the country," he said, pointing out that "women and children, the elderly, the wounded and sick, the people with disabilities are being used as bargaining chips and cannon fodder day after day, week after week, month after month."
"It is a grotesque situation," he said.
Zeid stressed that Aleppo was not the only place in Syria in need of desperate relief, pointing out that hundreds of thousands of civilians in other parts of the country were facing dire humanitarian conditions.
Especially those living under sieges imposed by the different warring sides were "in an utterly desperate situation, with many deaths, including of young children, as a result of severe malnutrition and lack of access to medical care," he said.
For instance, in the besieged town of Madaya, where at least 26 people have starved to death since the beginning of the year, he warned that "at least 300 people, including women and children, are in need of immediate evacuation."