As many as 500 migrants are feared to have drowned in the Mediterranean while attempting to reach Italy from Libya by boat last week, the United Nations refugee agency said on Wednesday.

A triple bombing killed at least 50 people in a predominantly Shiite suburb south of the Syrian capital of Damascus on Sunday even as a U.N. mediator held his first meeting with members of the main opposition group that seeks progress on humanitarian issues before it will join formal talks on ending the five-year civil war.

Russian President Vladimir Putin, pugnacious as always, called the Turkish downing of a Russian war plane "an enemy act" and rejected international efforts to oust Syrian leader Bashar al-Assad.

Turkey says it issued 10 warnings to the aircraft that violated its airspace Tuesday before responding "within engagement rules" near the Turkey-Syria border.

A number of cruise missiles launched from a Russian ship and aimed at targets in Syria have crashed in Iran, two U.S. officials told CNN Thursday.