MOSCOW — The Russian military and a main Syrian opposition group traded allegations Friday about whether new evidence indicates that either rebels or Syrian military used chemical weapons in the northern area of Aleppo where government forces are trying to regain control of areas they recently lost to insurgents.
Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said that ministry experts have found unexploded ordnance and fragments of munitil weons containing chlorine and white phosphorus on Aleppo's southwestern outskirts. Konashenkov said the discovery proves the militants have used chemical weapons against civilians and Syrian army soldiers.
The Syrian National Coalition, a main opposition group, however denied that rebels used chemical weapons in Aleppo saying that the shells that were fired are similar to those used by government forces and militias fighting with them. The SNC called on U.N. organizations to open an investigation into the case.
Russia, meanwhile, is asking the Organization for the Prohibition of Chemical Weapons to send its experts to the site, Konashenkov said, adding that munitions fragments and ground samples collected at the site will be handed over to the international chemical weapons watchdog.
The U.S. and its allies have pushed for sanctions on the Syrian government for using chemical weapons. Russia has questioned international investigators' conclusions linking chemical weapons use to the Syrian government and pointed at evidence of their use by the militants.
The U.N. Security Council has voted to extend the mandate of inspectors working to determine those responsible for chemical weapons attacks in Syria.
The announcement comes as the Syrian government and Russia appear to be preparing for an all-out offensive on the besieged eastern parts of Aleppo that are held by opposition fighters. Pro-Syrian media outlets in Lebanon have been reporting that heavy reinforcements have been arriving in Aleppo over the past weeks in preparation for the attack.
Aleppo, Syria's largest city and once commercial capital, has been the center of violence in recent months where government forces have besieged eastern rebel-held neighborhoods.
The insurgents had seized a couple of strategic areas in western Aleppo since they launched an offensive on government-held parts of Aleppo on Oct. 28 in an attempt to break the siege imposed on areas they have controlled since July. The siege on eastern Aleppo was coupled with a punishing bombing campaign by Syrian aircraft and supported by Russia, which has been backing the government of President Bashar Assad. Since late October, Russia said it would halt the airstrikes, amid rising civilian casualties, urging rebels to leave the territory.
Syrian troops launched a counteroffensive capturing much of the southwestern areas they lost as well as parts of Al-Assad district west of the city.
The Britain-based Syrian Observatory for Human Rights said warplanes carried out dozens of airstrikes on the western edge of Aleppo and nearby villages. It added that government forces are trying to regain control of the remaining parts of Al-Assad district that are still under rebel control.
The Aleppo Media Center, an activist collective, also reported intense airstrikes on Al-Assad district as well as an airstrike on the nearby village of Kfar Dael, saying it left dozens of people killed or wounded.
On Thursday, Jan Egeland, the special adviser to the U.N. envoy for Syria, said the last food rations in besieged eastern Aleppo will run out by next week. Speaking in Geneva, Egeland said the last time the over a quarter of million people inside east Aleppo received any humanitarian aid was in the beginning of July.
Meanwhile, jets from the Russian aircraft carrier Admiral Kuznetsov have been flying over Syria over the past few days to survey the area in preparation for future combat missions, the Interfax news agency reported Friday. It said that preparations are underway for the carrier and escorting ships to launch strikes against militants.
The carrier group's mission near Syria's shores marks the largest Russian naval deployment since the Soviet collapse. It allows the military to test its carrier-borne fighters in combat for the first time.
The Admiral Kuznetsov carries about 20 fighter jets, adding to some 30 warplanes Russia has at the Hemeimeem air base in Syria's coastal province of Lattakia.
Later on Friday, a video released by the Syrian government's military media that was apparently obtained from a dead insurgent showed militants mistakenly shooting at each other before recognizing they are comrades.
"They are comrades!" one fighter tells gunmen standing next to him before fighters on the other side approach them.
The video, apparently filmed with a fighter's helmet camera, showed fighters stepping out of an armored personnel carrier before coming under fire by government forces. The fighter then apparently gets wounded, as white smoke billows from a nearby building.
The violence in Aleppo came as Kurdish-led fighters captured more areas in the nearby province of Raqqa in battles with the Islamic State group.
Simko Derik of the U.S.-backed Syria Democratic Forces said that the first phase of the operation in Raqqa province has ended. Derik added in a statement that some 50 villages and 50 farms have been recaptured from IS, and some 150 extremists killed. He added that the second phase of the operation will aim to encircle the city of Raqqa, the de facto capital of IS' self-declared caliphate.
Associated Press writer Bassem Mroue in Beirut contributed to this report.