A blast near Syria's interior ministry has rocked the central Damascus district of Marjeh killing 13 people and injuring over 70 others, state television said, just a day after the country's prime minister survived a car bomb attack.
The Britain-based Syrian Observatory for Human Rights (SOHR) gave a lower toll, saying nine people were killed in Tuesday's blast.
The group, which relies on a network of activists based in Syria, did not immediately provide details on those reported casualties, but warned that the number of casualties was expected to rise.
Sharif Shehadeh, a Syrian member of parliament, told Al Jazeera "terrorism sponsored by Saudi Arabia, Qatar and the United States" was harming "innocent civilians".
Saudi Arabia, Qatar and Turkey have been at the forefront of backing Syrian armed opposition while the United States has provided "non-lethal aid" to groups fighting Bashar al-Assad's regime.
Regarding whether the recent bomb attacks are a response to the government counter-offensive on rebel strongholds, Shehadeh said: "The Syrian army is doing [an] excellent job in the Damascus suburbs and [the] countryside, as they have directed a big blow to the terrorists in many of the areas they are based in. The Syrian army and state is closing in on them day after day."
On Monday an explosion that targeted Prime Minister Wael al-Halqi's envoy in central Damascus damaged cars and caused casualties, state media reported.
The car bomb, which exploded as his convoy passed through the upscale al-Mazzeh neighbourhood, killed one of his bodyguards and five other people, according to SOHR.
Damascus has seen a wave of major bombings in recent weeks, including on April 9, when a massive blast in the centre of the city killed at least 15 people.
Tuesday's attack came as the British charity Oxfam warned that the human cost of Syria's conflict had risen beyond all expectations.
In a report, Oxfam said there were already more than 1.3 million Syrian refugees in neighbouring countries. Inside Syria itself, 6.8 million people struggle in urgent need of assistance, it said.
The money to help some of the refugees and displaced people is running out, Oxfam said.
UN appeals have received only half of the funding they sought – to help far fewer people than they now need to assist, according to Oxfam.
The charity's humanitarian programme is also struggling with insufficient funds to help as much as it needs to, despite the generosity of its supporters and the public, the report said.