The UN has described the situation in the Syrian city of Aleppo as “catastrophic", after dozens of people were killed in a series of air strikes, including in an attack on a hospital.
At least 20 people, including two doctors and three children, were killed when a series of air strikes, which hit a Medecins sans Frontieres-backed hospital and nearby buildings in a rebel-held part of Aleppo overnight on Thursday.
The dead include one of the few paediatricians remaining in the city's opposition-held areas and a dentist, activists said.
Jan Egeland, chairman of the UN humanitarian task force for Syria, said there had been a "catastrophic deterioration in Aleppo over the last 24-48 hours,” adding the humanitarian lifeline for much of the countries’ citizens was “at sake”.
“The stakes are so incredibly high because so many civilian lives are at stake, so many humanitarian health workers and relief workers are being bombed, killed, maimed at the moment that the whole lifeline to millions of people is now also at stake," Mr Egeland told reporters in Geneva after a meeting of major and regional powers in the International Syria Support Group (ISSG).
The chief Syrian opposition negotiator, Mohammed Alloush, blamed the government of President Bashar Assad for the deadly air strikes on Aleppo.
Mr Alloush, who was one of the leading negotiators of the opposition in the Geneva talks, described the air strikes as one of the latest "war crimes" of Assad's government.
The upsurge in violence comes amid concerns that the 27 February ceasefire has been fraying in the past weeks as casualty figures from the violence mount, particularly in Aleppo and northern Syria.
Air strikes earlier this week also targeted a training centre for the Syrian Civil Defence, killing five of its team in rural Aleppo.
Since 19 April, nearly 200 people have died, including at least 44 in an air strike on a market place in rebel-held area in northern Idlib province, as well as dozens of civilians in government-held areas from rebel shelling.
The UN envoy for Syria, Staffan de Mistura, has said the cessation of hostilities agreed in talks between the Western- and Saudi-backed opposition and envoys from Assad's government, which has the backing of Moscow, "hangs by a thread".
UN relief operations are seeking access to 35 besieged and hard-to-reach areas during May.
Operations have reached 778,175 Syrians this year in besieged or relatively inaccessible areas, however Mr Egeland says: “All of that may now be lost if the ... fighting and the violence and bombardment of civilians, health workers, hospitals, relief workers continue."
Additional reporting by agencies
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