Beirut, Asharq Al-Awsat—Damascus was rocked on Thursday by a car bomb that exploded in the heart of the city, close to the headquarters of Syria’s ruling Baathist Party. State media say that the blast killed over 50 people and wounded more then 200 more, and press reports indicate that it damaged several buildings in the city’s Mazraa district, including the Russian embassy.

The bomb is understood to have detonated at a checkpoint manned by Syrian security forces, though many of the casualties were said to be civilians. Eyewitnesses told reporters that at least one child was killed by flying glass.

The London-based Syrian Observatory for Human Rights, a Syrian opposition group, reported that two other bomb attacks were carried out shortly afterwards close to state security facilities in Damascus’s Barzeh district, though it is not known if the attacks are connected.

The bombings follow several days of intense battles in and around Damascus, with rebels based in the city’s southern and eastern suburbs seeking to contest government control of strategic road junctions close to the district of Jobar. Rebels have also succeeded in recent days in striking some targets in Damascus with mortar fire, including the Tishreen Palace and a soccer stadium. Government forces have responded with air strikes.

On the Syrian-Lebanese border, tensions between elements of the Free Syrian Army (FSA) and Lebanese Hezbollah have been raised by an ultimatum issued by FSA’s chief of staff, Selim Idriss, who accused the organization of shelling rebel-held towns in Homs province from Lebanon’s Bekaa valley.

General Idriss warned on Wednesday that Hezbollah had 48 hours to stop attacks before the FSA retaliated, telling the AFP news agency: “As soon as the ultimatum ends, we will start responding to the sources of fire.”

Hezbollah commanders deny that their forces are involved in any operations in Syria, but admit that some members of the organization have travelled across the border to take part in the fighting on their own initiative.

Elsewhere in Lebanon, a judge indicted two Syrian army officers and a former Lebanese cabinet minister with involvement in a plot to bomb targets in Lebanon at the behest of the Syrian government.

According to a Lebanese news agency, the judge demanded the death penalty for Michel Samaha, a former Minister of Information, and two senior Syrian army officers: Brigadier-General Ali Mamlouk, and a colonel identified only as Adnan. The indictment alleges that Mr Samaha received explosives from the colonel, which he then transported across the border after promising to recruit people to carry out attacks on Syrian rebels and arms smugglers based in northern Lebanon.