UNITED NATIONS (Reuters) - Turkey called on Tuesday for a more robust international effort to end Syria's civil war, saying the global community had a responsibility not to abandon the Syrian people.

Turkish President Abdullah Gul made the remarks while addressing the U.N. General Assembly in New York, and said the international community was responsible for ending the conflict, which has killed more than 100,000 people, according to U.N. estimates.

Turkey, once an ally of Syrian President Bashar al-Assad but now one of his fiercest critics as he fights rebels trying to oust him, called for U.N. Security Council action last month after a deadly chemical weapons attack near Damascus.

"This conflict has evolved into a real threat to regional peace and security," Gul said. "Any recurrence of the proxy wars of the Cold-War era will plunge Syria into further chaos."

Gul said Turkey welcomed a U.S.-Russian agreement to remove Syria's chemical weapons arsenal, but said the world must not allow Assad's government to "avoid responsibility for its other crimes."

"This conflict neither began with the use of chemical weapons, nor will it end with an agreement to eliminate them," Gul said.

He criticized what he called "balance-of-power politics" that had helped to prolong the war, and called for a strategy led by world powers and Syria's neighbors to end the civil war.

"In short, we cannot and shall not leave the Syrian people to their fate," he said. "The burden of ending Syria's plight now rests on the shoulders of the international community. Strong words of support must now be matched by real deeds."

(Reporting by Yeganeh Torbati; Editing by David Brunnstrom)