Fighting between Syrian troops and rebels continued into the night on Monday after Damascus witnessed some of the worst violence in the tightly controlled capital since the country's crisis began 16 months ago.
Clashes rocked several neighbourhoods in the southwest of the city for a second day on Monday. Rebels fired grenades at tanks and troops while shelling by government forces sent black smoke billowing into the sky.
"I can hear shelling, explosions and gunfire every once in a while," a Kfar Souseh resident told Al Jazeera in the early hours of Tuesday.
Troops deployed armoured vehicles near the historic neighbourhood of Midan, and activists said residents were fleeing nearby Tadamon,
The fighting briefly closed the highway linking the capital with Damascus International Airport on Monday.
The town of Qatana, 20km away from the capital, was also shelled on Monday. Elsewhere, government troops shelled the besieged Homs districts of Khaldiyeh, Jourat al-Shayah and Qarabees.
To the north, government forces raided the central city of Hama, scene of fierce clashes and a series of loud blasts, the Britain-based Syrian Observatory for Human Rights reported on Monday.
West using 'blackmail'
Meanwhile, Russia has said it would block moves at the UN Security Council to extend a UN monitoring mission in Syria if Western powers did not stop resorting to "blackmail" by threatening sanctions against Damascus.
Sergei Lavrov, Russian foreign minister, staked out a tough position on Monday before talks in Moscow with UN envoy Kofi Annan, dismissing international pressure on Russia and China to stop propping up Syrian President Bashar al-Assad.
His comments are likely to dim Western diplomats' hopes that Moscow is trying to find a face-saving way to drop its support for Assad and accept that he should have no role in a transition.
"To our great regret, we are seeing elements of blackmail," Lavrov told a news conference before Annan started a two-day
visit that will include talks on Tuesday with President Vladimir Putin. "This is a counter-productive and a dangerous approach."
Rami Khouri, director of the Esam Fares Institute at the American University of Beirut, told Al Jazeera that the Russian position is less about supporting Assad and more about "saving face".
"The Russians are a big world power. Lives, money, alliances, respect, stature - all of these are negotiable to them, as they are to the Americans," said Khouri.
"The Russians are caught in a bind because they've taken a stand on Syria which is not really about saving the Assad regime, but rather saving face for the Russians, and generating international respect for the Russian government."
Meanwhile, Morocco has asked Syria's ambassador to Rabat to leave the country, prompting Damascus to ask Rabat's envoy to leave.
As violence continued, the International Committee of the Red Cross said on Sunday it now considers the Syrian conflict a civil war.
The Geneva-based group's assessment could have implications for prosecutions for war crimes and means that international humanitarian law applies throughout the country.
Josh Lockman, an international law professor at the University of Southern California, said the assessment does not make any significant difference on the ground, but is "of tremendous significance for the long term".
"With this application of international humanitarian law to the conflict, key government officials could be held responsible for both massacres against civilians and also for the treatment of captured combatants, in this case rebel fighters, to the degree they're abused, harmed or killed," he told Al Jazeera.