Syrian army helicopters on Saturday dropped barrel bombs on Islamic State-controlled areas of Aleppo, killing 71 people and wounding dozens more, most of them civilians.
The British-based Syrian Observatory for Human Rights, which documents violence on the ground in Syria through a network of activists, said 59 men were killed in an airstrike on a busy market called Souk al-Hal in the town of al-Bab in Aleppo's countryside. At least another 12 people were killed in a blast in the rebel-held Shaar neighborhood of Aleppo, most of them from the same family.
The U.N. special envoy for Syria, Staffan de Mistura, said the bombing of a civilian market area "deserves the most strong international condemnation." He said "it is totally unacceptable that the Syrian air force attacks its own territory in an indiscriminate way," and added that the "use of barrel bombs must stop."
In a Twitter message, the Islamic State called the al-Bab attack a "devastating massacre" committed by the Syrian army.
Syrian President Bashar al-Assad has denied the air force uses barrel bombs — crude weapons made of oil drums, gas cylinders or water tanks packed with explosives and scrap metal.
State news agency SANA did not report on these specific raids but, citing a military source, said the armed forces had targeted Islamic State militants in Aleppo province's eastern countryside and hit "terrorist organizations" on a road running north to the border, as well as to the south of Aleppo city and within the city itself.
Meanwhile, Islamic State militants carried out two suicide bombings targeting Syrian troops in the predominantly Kurdish city of Hasakah.
The United States and its allies said they continued their airstrikes on Islamic State positions Friday into Saturday, hitting 16 targets in Iraq and another six in Syria. The military command said it deployed bomber and fighter aircraft and drones to hit Islamic State command centers and destroy the insurgents' weaponry.
The U.S. Central Command announced that two of its officials met in recent days with Syrian opposition and civilian leaders to discuss the ongoing American effort to train and equip forces fighting Islamic State insurgents in Syria.
More than 220,000 people have been killed in the Syrian uprising against the Assad regime since the unrest began more than four years ago.
Syria's military had recently been hit by a series of setbacks.
Insurgents, including al-Qaida's Syrian wing, Nusra Front, celebrated inside the last government-held town in Idlib province on Friday after capturing it the night before, while the Islamic State group has secured its grip on the ancient central city of Palmyra.
In Syria's northeast, clashes erupted between pro-government forces and Islamic State fighters to the south and southeast of Hasakah city, the Observatory said Friday, after the al-Qaida offshoot planted a bomb on the edge of the city.
Hasakah province is strategically important because it lies next to Islamic State-held territory in Iraq, where the group is back on the offensive after losing the city of Tikrit at the start of the month.
SANA said the Syrian military had foiled an attack on Hasakah and that it had been targeting Islamic State in the countryside with the help of Kurdish YPG militia. The YPG, which has fought the fiercest battles against Islamic State in the northeast, says it does not coordinate with the Syrian military.
Material for this report came from Reuters, AFP and AP.