Blast, clashes kill dozens at intelligence HQ in Syria’s Aleppo — monitor

BEIRUT — Dozens were killed Wednesday when Syrian rebels set off a powerful tunnel explosion targeting an intelligence headquarters in Aleppo and clashed with regime forces, a monitor said.

The Syrian Observatory for Human Rights said the blast hit a building housing the air force intelligence offices in the west of Syria's second city and was followed by heavy clashes.

"The explosion and the fighting caused dozens of deaths on both sides," it said, adding that part of the building had collapsed.

An AFP journalist in eastern Aleppo said the blast was loud enough to be heard across the city and some residents said it had felt like an earthquake.

A Syrian military source confirmed the explosion and said clashes were continuing.

"Gunmen blew up a tunnel that they dug [into the regime-controlled sector] and then attacked the area surrounding the air force intelligence headquarters," the source said.

"There are now ongoing clashes and the Syrian air force is hitting the positions of the gunmen in the area," the source said.

Al Qaeda's affiliate in Syria, Al Nusra Front, said on its Twitter feed that its forces, along with other rebel factions, had "stormed the air force intelligence offices and surrounding buildings".

Setting off explosives from tunnels dug into government-controlled area has become a favoured tactic of Syria's rebels, especially in Aleppo.

A similar blast from explosives planted in a tunnel under Aleppo's Old City in December killed at least seven government groups.

Rebels also last May detonated explosives under the city's famed Carlton Hotel, which government forces had been using as a base.

Fighting in Aleppo erupted in mid-2012, and control of the city — once Syria's main commercial hub — has since been divided between rebels on the eastern side and the regime in the west.