Dozens of people, including children, have died in bomb attacks by the Syrian regime on the rebel-held city of Aleppo, opposition activists claimed Sunday.
Sky News, citing the Britain-based Syrian Observatory for Human Rights, reported that 85 people were killed, including 65 civilians and 10 children. The attacks were carried out by helicopters which dropped barrels packed with explosives, fuel, and scraps of metal on several areas of the city.
Of the 20 non-civilians killed, the Observatory reported that 10 were fighters with an Al Qaeda-linked group, the Al-Nusra Front, who were killed when their headquarters was hit by one of the so-called "barrel bombs." Another 10 bodies could not be identified.
Aleppo has been a key battleground in Syria's civil war since rebels swept into the city in mid-2012 and wrested most of the eastern and southern neighborhoods from the government. Since then, the fighting has settled into a bloody grind, with neither side capable of mounting an offensive that would expel its opponents from the city.
But over the past two months, President Bashar Assad's air force has ramped up its aerial campaign on rebel-held areas of Aleppo.
On Sunday alone, Syrian military aircraft targeted 15 opposition-controlled neighborhoods, said an activist who goes by the name of Abu al-Hassan Marea.
The Britain-based Syrian Observatory for Human Rights monitoring group said the Tariq al-Bab district on the eastern edge of the city was the hardest-hit, with at least eight barrel bombs raining down on it Sunday. Marea said one of the air raids in the neighborhood struck a vegetable market and another landed near a mosque.
An amateur video posted online showed a helicopter circling in the blue sky, and then a barrel plummeting from the aircraft until it slams into buildings on the horizon, sending a pillar of smoke and dust into the air. The video appeared genuine and corresponded to other Associated Press reporting of the events depicted.
This is not the first time that Assad's air force has waged an intense campaign over Aleppo. In December, military helicopters pounded rebel-held districts of the city with barrel bombs, leveling buildings, burying people under the rubble and killing more than 500 people over a two-week stretch.
The misery in Aleppo was then compounded in early January by an outburst of rebel-on-rebel fighting, which has weakened the opposition's grip on parts of the city.
Over the past two weeks, Assad's forces have slowly chipped away at the rebels' hold on neighborhoods in southeastern Aleppo. While the advances have been small, they still mark the most significant government gains in the divided city since opposition fighters seized the areas in mid-2012.
As intense as the airstrikes have been, the rebels' position in the city and across northern Syria has been undermined to a greater degree by the bloody bout of infighting that pits the al-Qaida-linked Islamic State of Iraq and the Levant against an array of ultraconservative brigades and more moderate factions.
The rebel clashes have killed more than 1,400 people since they began a month ago, and the fighting shows little sign of coming to an immediate close.
On Saturday, a twin suicide bombing killed 26 people, including a senior military commander of the Tawhid Brigade, a prominent rebel group opposed to the Islamic State.
The attack, widely blamed by both pro- and anti-al-Qaida activists on the Islamic State, targeted the base of its rivals in the Tawhid Brigade and killed senior leader Adnan Bakkour, said Observatory director Rami Abdurrahman.
The Islamic State also killed another prominent commander, Abu Hussein al-Dik of Suqour al-Sham, on Saturday near the central city of Hama, the Observatory said. Abdurrahman said al-Dik was killed in an ambush outside of Hama, where he was traveling to try to help rebels encircled by Islamic State fighters.
Both the Tawhid Brigade and Suqour al-Sham are part of the Islamic Front, a powerful alliance of seven Islamist rebel factions that united in November. The Islamic Front has emerged as a heavy weight in northern Syria, and has been a driving force in the fight against the Islamic State.
Analyst Charles Lister of the Brookings Doha Center said the Islamic State "appears to be targeting particularly strategic locales and individuals in its continuing operations against perceived enemy rebels."
The Associated Press contributed to this report.