Turkish President Recep Tayyip Erdogan has warned against what he called "the security and humanitarian risks" of an upcoming Syrian army operation to liberate Idlib Province, which holds the largest concentration of militant groups, including those backed by Ankara.
In an article in today's Wall Street Journal, he calls on the global community to take action, and warns that "the entire world stands to pay the price" otherwise.
The UN has estimated 800,000 people could be displaced by an attack.
Two children were killed in heavy barrel bomb attacks on a village in Idlib's south Sunday, a day after 10 civilians died in shelling across the rebel zone, the Syrian Observatory for Human Rights monitoring group said.
Regarding the peace talks, de Mistura said earlier in Geneva that his discussions with the senior Russian, Turkish and Iranian officials taking place on September 10 and September 11 for the new process are the best "roadmap we can see".
Other aid organisations also operate in the area, but their support is mostly limited to providing supplies to civilians already living in the existing border camps. "Conventional weapons are responsible for far more deaths", he said.
De Mistura's talks Tuesday came as top United Nations officials were expressing deep concern about the humanitarian consequences of an expected assault on Idlib, where an imminent offensive by the Syrian forces, aided by Russian Federation, is likely to take place.
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Iran and Russian Federation have backed a military campaign on Idlib involving Syrian President Bashar Assad's forces, despite Turkey's pleas for a ceasefire.
In the eastern province of Deir Ezzor, US-backed fighters fought to oust IS from the town of Hajin on the east bank of the Euphrates, the most significant remnant of the sprawling "caliphate" the jihadists once controlled spanning Syria and Iraq. They are believed to be holding them in the Safaa area.
The footage was filmed by several Middle Eastern news channel crews and one unnamed USA broadcaster, the Defense Ministry said.
Kalin said Turkey expects all parties to make "constructive" contributions and agree on a political solution on Syria. "There is no doubt that such provocations are being prepared", he added, noting that terrorist groups operating in Syria are on the defensive and are getting desperate, as the Syrian government's mission to combat and defeat the terrorist threat continues to make progress.