BEIRUT (AP) – Government troops fought back rebels near the airport of battle-scarred Aleppo, Syria's state media said Friday, in the first official acknowledgement combat had neared a strategic gateway to the country's largest city.

As fighting raged in both Aleppo and the Syrian capital Damascus, the United Nations announced that Lakhdar Brahimi, a former Algerian foreign minister and veteran U.N. diplomat, would serve as the world body's new peace envoy, aiming to resume efforts for a diplomatic solution to what has become an intractable civil war.

Brahimi, who previously served as envoy to Iraq and Afghanistan, replaces former U.N. Secretary-General Kofi Annan, who announced he would leave the post by the end of this month after failing to bring about a cease-fire despite months of negotiations.