Heavy fighting between the army and rebels is reported to be spreading around the Syrian capital, Damascus, with plumes of smoke seen rising from the suburbs.
The BBC says activists spoke earlier of government forces using tanks and artillery against the Free Syria Army in the Tadamon, Kfar Sousa, Nahr Aisha and Sidi Qadad neighbourhoods in the southern suburbs.
Now, unconfirmed reports say the fighting has spread to al-Lawan in the south-western outskirts.
The fighting is the heaviest it has been in Damascus since the revolt against President Bashar al-Assad began 17 months ago.
A BBC correspondent, reporting from Lebanon, says clashes between government forces and Free Syrian Army rebels seem to be creeping ever closer to the heart of Damascus and the centre of the regime's power.
Residents were said to be fleeing some areas, while in other parts of the city protesters blocked motorways with burning tyres.
The Syrian government earlier called a news conference in Damascus to deny heavy weapons were used in an attack on the village of Tremseh on Thursday.
The mandate for a United Nations' monitoring mission is due to run out on Friday.
Syria now under Geneva rules
The International Committee of the Red Cross says the conflict in Syria can now be classed as a civil war.
That means all combatants can be subject to the Geneva Convention, which gives warring parties the right to use appropriate force, but also allows for war crimes prosecutions.
The Red Cross says there is now a non-international armed conflict right across the country. Previously this categorisation applied only to three locations:, Homs, Hama and Idlib.
Mr Assad said in a speech on 26 June the country was in a state of war.
Annan, Lavrov to talk
The fighting came as United Nations and Arab League envoy Kofi Annan prepared to meet Russia's foreign minister Sergei Lavrov for talks on the Syrian crisis. Russia has been backing the Syrian regime.
Mr Annan is expected to urge Mr Lavrov to put pressure on the Syrian authorities to begin a political transition, although the BBC's Moscow correspondent says there is little sign the Kremlin is ready to do that.