Syria's army says it is offering rebel fighters in besieged eastern Aleppo an opportunity to leave the city with their lives.

Army spokesman Brig. Gen. Samir Suleiman said those who choose to stay will face "inevitable death."

He spoke to The Associated Press in Aleppo, where government forces and allied militias are seeking to collapse an opposition pocket on the city's eastern side.

"We will continue fighting until we restore stability and security to all neighborhoods" of Aleppo, Suleiman said.

He said the Syrian army has retaken more than 50 percent of neighborhoods in eastern Aleppo.

He also said that efforts to retake Aleppo's historic quarters known as Old Aleppo will be the most difficult, adding that the army will use infantry and special forces.