Damascus is still under the control of government forces loyal to the Syrian President.
Syria’s official news agency, SANA, accused what it called “terrorists” of carrying out two mortar attacks in the district of Mezze 86 in western Damascus.
The district, inhabited mostly by Alawites, al-Assad’s Shiite linked Muslim sect, is home to government offices near the presidential palace.
There is also a small airport in the district used by foreign officials and dignitaries visiting the country for talks with al-Assad, according to activists.
“The area is highly secured by al-Assad’s troops, but the rebels had infiltrated it, which shows that the rebels are gaining force on the ground,” activist Haytahm al-Abdullah told dpa from Damascus.
Residents living in the area told dpa they had heard at least three massive explosions followed by gunfire.
Following the attack, the Syrian military sealed off streets and shut down schools.
“All roads in and out of the capital were blocked by army checkpoints,” one resident said on condition of anonymity for fear of punishment by authorities.
A shadowy rebel group, calling itself the Lions of Islam, claimed responsibility, saying the Damascus attacks were retaliation
for “massacres” committed by al-Assad’s forces.
At least 11 people were killed in a car bombing on Monday in the same district, according to state media.
On a visit to neighbouring Jordan, British Prime Minister David Cameron said he hoped al-Assad would face justice for the “appalling crimes he has meted out” on Syrians.
Mr. Cameron visited the refugee camp of al-Zaatari, which shelters around 30 thousand Syrians displaced by the 20-month conflict.
“I am standing with the Syrian border just behind me, and every night 500 refugees are fleeing the most appalling persecution and bloodshed to come to safety, and, frankly, what we have done so far is not working,’’ he said.
A British government spokesman said Britain was to increase its humanitarian aid for Syrian refugees to more than 50 million pounds, making it the second biggest donor after the U.S.
The spokesman said Britain was planning to hold direct talks with Syrian rebels in a bid to unite the opposition. Britain has ruled out offering arms or military advice to rebels.
In Qatar, the Syrian National Council, the main opposition bloc, resumed talks to restructure its ranks and broaden its membership to include military factions inside Syria, opposition sources said.
Some 400 members of the SNC met late Wednesday and were due to choose a new 40-member general secretariat, which will include liberals, rebels as well as ethnic minorities and tribes from inside Syria. The new SNC secretariat is then expected to meet and elect a new politburo and a president to replace the group’s current chief, Abdel Basset Sayda, who took up the post in June.
Formed in October 2011, the council, currently made up of exiles, has been criticised by the U.S. as not representative of the Syrian opposition. Washington has reportedly backed a plan suggested by the prominent Syrian dissident, Riad Seif, to create a 50-member opposition body and a government in exile.
The plan is expected to be discussed at a wider meeting of opposition groups on Thursday in Qatar.
Senior Arab officials, including Arab League Chief, Nabil al-Arabi, are due to attend the talks.
“It is important to unify the opposition’s ranks and visions, especially because everyone knows that the regime in Syria will not stay for long, and one day there will be a new situation in Syria,’’ Mr. Al Arabi told reporters late on Wednesday in Cairo before leaving for Doha.