BEIRUT — Antigovernment activists in Syria said the military fired Scud missiles into at least three rebel-held districts of Aleppo on Friday, flattening dozens of houses, killing at least 12 civilians and burying perhaps dozens of others under piles of rubble.
The assertion, which appears to be corroborated by videos posted on the Internet, came one day after Syrian government targets in central Damascus were hit by multiple car bombings that were among the deadliest and most destructive so far in the nearly two-year-old conflict.
The report said the Hamra, Tariq al Bab, and Hanano areas of Aleppo were hit with Scuds, which are not known for their accuracy; it was the second report this week of the military using such missiles on rebel-held areas.
Aleppo, once Syria’s commercial capital, has become one of the focal points of rebellion in the uprising against President Bashar Assad. On Tuesday, according to activists in the city, a Syrian missile leveled part of Jabal Badro, another neighborhood controlled by the rebels.
The Syrian Observatory for Human Rights, a Britain-based group with contacts inside Syria, said in a statement that the victims of missile explosions in Aleppo on Friday included children and that the number of victims ‘‘is expected to rise significantly because there are dozens of wounded under the rubble.’’
State-run news media made no immediate mention of the Aleppo attacks. The website of Syria’s official SANA news agency was dominated by the aftermath of the car bombings in Damascus on Thursday, which killed more than 70 people. The ferocity and scope of those bombings were unusual for central Damascus, which until now has been largely insulated from the carnage and destruction wrought by the conflict in the city’s outer suburbs and other parts of the country.
Most of the casualties in Damascus were caused by an especially powerful bomb near the headquarters of Assad’s Ba’ath Party and the Russian Embassy, which were both damaged, according to Russian news reports and witnesses contacted in the capital. SANA reported that a hospital and neighboring schools also were damaged.
No group has taken responsibility for the Damascus bombings but the government has said they were carried out by terrorists, its generic description for the alliance of armed rebels seeking to oust Assad.
The National Coalition of Syrian Revolutionary and Opposition Forces, the main Syrian group for the opposition, which was meeting in Cairo at the time, condemned the bombings, as did its Western supporters, including the United States.
Victoria Nuland, a State Department spokeswoman, told reporters on Thursday that the United States denounced such bombings as ‘‘indiscriminate acts of violence against civilians or against diplomatic facilities.’’ The attacks violate international law, she said, adding that ‘‘perpetrators on all sides have to be held accountable.’’
Nonetheless, the bombings appeared to create a new source of diplomatic friction between the United States and Russia, which has supported the Syrian government during the conflict and has rejected any proposed solution that would force Assad to relinquish power.
Russia’s mission to the United Nations accused the United States of blocking its attempt to seek approval of a Security Council statement that would have condemned the Damascus bombings as terrorism. The US mission denied the accusation, saying it only requested that the Russian statement include a paragraph that also condemned the Syrian government’s ‘‘continued, indiscriminate use of heavy weaponry against civilians.’’