Syrian rebels shelled a key area of Damascus, home to President Bashar al-Assad's Alawite minority, embassies and government buildings on Wednesday, as they stepped up attacks on his power base.
Britain, meanwhile, said it was to open talks with the rebels in a bid to help end the violence, as the main opposition Syrian National Council said it hoped resolving the conflict would top re-elected US President Barack Obama's agenda.
Syria's neighbour Turkey revealed it was in talks with NATO over the possible deployment of Patriot missiles on its soil amid the escalating conflict, as the Arab League said Assad's regime would not stay in power long.
The shelling in Damascus of the mainly Alawite Mazzeh 86 district came as rebels increasingly target Assad's supporters in the minority, an offshoot of Shiite Islam.
Sectarian divides are a key factor in Syria's armed rebellion, with many in the Sunni Muslim majority frustrated at more than 40 years of Alawite-dominated rule.
State news agency SANA reported that shelling had hit a home and mini-bus carrying passengers in Mazzeh 86, which lies beneath Assad's hilltop presidential palace, killing at least three civilians.
Syrian children play on the rubble of buildings in the northern Syrian town of Atareb in the Aleppo province.
The Syrian Observatory for Human Rights, a Britain-based watchdog that relies on a network of activists and medics on the ground, confirmed the shelling and said at least three civilians were killed and 12 wounded.
It previously reported a car bombing in an Alawite area of the suburb of Qudsaya on Tuesday that killed 19 people and another on Monday in Mazzeh that left 13 dead.
"The attacks on Mazzeh are a significant turning point because for the first time the Alawite community, which has never been targeted as such, is directly associated with the regime and targeted for this," said Fabrice Balanche, an analyst with the Mediterranean and Middle East Studies and Research Group in Paris.
Fighting raged and air strikes hit in other parts of the country, while SANA reported that a judge was killed when a car bomb exploded outside his home in the northeast of Damascus.
In the town of Nabak near Damascus, a suicide bomber drove a van loaded with explosives into an army position, killing six soldiers, the Observatory said, adding that at least 100 people had been killed across Syria on Wednesday.
It said more than 37,000 people had now died since the uprising against Assad's regime erupted in March 2011, first as a protest movement and then an armed rebellion after repression.
-- Britain to contact rebels --
Britain announced it would begin direct talks with military figures in Syria's armed opposition groups, as Prime Minister David Cameron called for a new international approach to ending the conflict.
A picture released by the Syrian Arab News Agency (SANA) shows the site of an explosion in western Damascus. Syrian rebels shelled the area which is home to President Bashar al-Assad's Alawite minority, embassies and government buildings, as they stepped up attacks on his power base.
In a statement to parliament, Foreign Secretary William Hague said Britain would not supply weapons to the rebels and said officials would stress to the opposition groups the importance of respecting human rights.
Cameron himself toured a desert refugee camp for Syrians in northern Jordan on Wednesday.
"I am hearing appalling stories about what has happened inside Syria so one of the first things I want to talk to Barack about is how we must do more to try and solve this crisis," he said.
As the Syrian National Council met in the Qatari capital Doha, leading members said Obama should work to end the crisis following his re-election.
SNC chief Abdel Basset Sayda told AFP he hopes the US administration would now "address the Syrian crisis with seriousness and responsibility in order to end the massacres and destruction."
Washington has voiced increasing frustration with the SNC for not fully representing the opposition, and the talks in Qatar will see an initiative put forward to form a new government-in-exile to represent the opposition.
SNC members began voting on a new leadership for the group Wednesday.
Preparing to head to the opposition talks on Thursday, Arab League chief Nabil al-Arabi said it was important for the opposition to unite, "especially because everyone knows that the regime in Syria will not remain for long."
In Ankara, a foreign ministry spokesman said Turkey was in talks with NATO about the possible deployment of Patriots, primarily used as anti-ballistic missiles, but Prime Minister Recep Tayyip Erdogan said no request had yet been made.
Turkey has beefed up border security with tanks and anti-missile batteries in the face of the deadly conflict across the border, which has spilled over into each of Syria's neighbours.