Turkish President Tayyip Erdogan said earlier that a "secure zone" would pave the way for the return of 1.7 million Syria refugees currently sheltering in Turkey after fleeing their country 4 year war.

"What you don't want to do is call something a safe zone, people flee to it, but it hasn't got sufficient protection," O'Brien told reporters after briefing the U.N. Security Council on the humanitarian situation in Syria, Reuters reports.

"As our primary objective is the protection of civilians we need to make sure there is protection in place and that is not always the role of the humanitarians, it needs to be established by others," he said.

Turkey and the United States are working on plans to provide air cover for Syrian rebels (Armed terrorists opposition of Syria government) to what they call buffer zone in the Turkish border. But U.S. officials claimed the aim was not to create a civilian "safe zone."

O'Brien said the United Nations was in constant contact with all the parties regarding new proposals.

Turkish warplanes for the first time on Friday, joining a U.S.-led coalition that has been bombing so-called “Islamic State” targets in Syria for the past 10 months. Meanwhile turkey apparently attacks Kurdish position in place of ISIS.

"We are facing this kind of escalation by the Turkish government, it's an irresponsible action," Syria's U.N. Ambassador Bashar Ja'afari told reporters on Tuesday.

In 2011 unrest, ISIS terrorists have taken advantage of the chaos to seize swathes of territory in Syria and Iraq and declare a caliphate.

The United Nations has said that some 220,000 people have been killed and 7.6 million are internally displaced in Syria. Another 4 million people have fled the country, which O'Brien said was the largest refugee population from a single conflict in more than 25 years.

"Syria today ... is the most acute, unrelenting and shameful blot on the world's humanitarian conscience," said O'Brien, who hopes to visit Damascus next month.