BEIRUT (AP) — Syrian militants, including members of al-Qaida's local branch, attacked a government intelligence center in the northern city of Aleppo, damaging much of the building by blowing up a tunnel under it, activists said Tuesday.
The attack on the Air Force Intelligence headquarters began late Monday night and lasted until early Tuesday, said Aleppo-based activist Ahmad Hamed via Skype. He claimed the attack killed dozens of government troops.
The Britain-based Syrian Observatory for Human Rights said the fighting killed 13 militants and killed and wounded more than 20 troops and pro-government gunmen. There was no immediate word from the government on the attack.
Rebels and members of al-Qaida's Nusra Front have launched several past assaults on the Aleppo intelligence center, where dozens of detainees were once held. Activists say repeated attacks there forced the government move detainees elsewhere.
Aleppo, Syria's largest city, became key battlefield after rebels launched an offensive there in July 2012.
The violence came as Human Rights Watch said Tuesday that evidence "strongly suggests" that Syrian government forces used toxic chemicals in several barrel bomb attacks in northwestern Syria last month.
Human Rights Watch quoted rescue workers as saying the attacks in Idlib province from March 16 to March 31 affected at least 206 people, including 20 civil defense workers. It said one attack killed six civilians.
The group's report said people near the sites of three attacks exhibited symptoms consistent with exposure to toxic chemicals, and gas canisters were among the barrel bomb remnants. It said witnesses also described a strong chlorine smell, though the group acknowledged it could not absolutely confirm chemical weapons were used.
Chlorine was first introduced as a chemical weapon in World War I with disastrous effects as gas masks were not widely available. While chlorine has many industrial and public uses, as a weapon it chokes victims to death.
Most nations banned its use in war in the Geneva Protocol of 1925. The government of Syrian President Bashar Assad has been accused repeatedly of using it in the civil war. Forces loyal to Assad have blamed rebels for such attacks.