The UN Secretary-General Ban Ki-moon has highlighted a string of crisis facing the international community in a world that may seem like it is falling apart.

Addressing world leaders on Wednesday at the opening of the UN General Assembly's ministerial meeting in New York, the UN chief painted a grim picture of what lays ahead, listing the outbreak of disease, return of Cold War spectres, and violence in the Middle East as part of challenges that needs confrontation.

"But leadership is precisely about finding the seeds of hope and nurturing them into something bigger," Ban said. "That is our duty. That is my call to you today."

The secretary-general said the world is witnessing "unspeakable acts and the deaths of innocents."

Leaders from more than 140 countries have little to offer as solutions for challenges that range from widespreading radicalisation in the Middle East and Africa, outbreak of the deadly Ebola virus and worsening world climate that has driven thousands to the streets on Monday around the world.

Diplomats are corned that the Islamic State in Iraq and Levant (ISIL) will overshadow all topics, as the US tries to put together a global coalition to root out a group that pushed at least 80,000 Syrian Kurds into Turkey over the past few days, to escape the violence.

The first US and Arab air strikes in Syria were delivered Monday night, following four years of reluctance on whether to militarily intervention to end a civil war that has killed over 190,000 people, as troops of Syrian President Bashar al-Assad brutally clampdown on rebels who sought his ouster.

Source: Agencies