The clashes briefly closed the highway linking the capital with Damascus International Airport to the city's south – an unprecedented development, said Mustafa Osso, an activist based in Syria.
"It seems there is a new strategy to bring the fighting into the center of the capital," Osso told The Associated Press, referring to the rebels who fight under the banner of the Free Syrian Army. "The capital used to be safe. This will trouble the regime."
The Britain-based Syrian Observatory for Human Rights and Osso said the fighting was concentrated in the districts of Kfar Souseh, Midan and Tadamon.
There have been sporadic clashes in Damascus in recent months, although President Bashar Assad's forces remain firmly in control of the capital. Many of the Damascus suburbs, however, have risen up against the regime, prompting a ferocious response from the military in an attempt to clear out rebel fighters from the towns that ring the capital
An opposition flag on a Syrian tank (Photo: Reuters)
On Monday, activists reported government attacks in the Damascus suburb of Qatana.
Rami Abdul-Rahman, who heads the Observatory, said Mondays' fighting was taking place about 2 kilometers (1 mile) from the airport highway.
The clashes come as Russian Foreign Minister Sergey Lavrov on Monday accused the West of using blackmail to secure a new UN Security Council resolution that would authorize the use of force in Syria.
UN special envoy Kofi Annan was expected in Moscow on Monday to discuss the Syria crisis.
The UN's Human Rights Council estimates that more than 17,000 people have been killed in Syria since the uprising began.
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