'We really don't know what's going to happen': Uncertainty grips Damascus

Syria's state news agency claimed "sleeper cells" were publishing clips on social media from public areas of Damascus to suggest they had taken control of them "with the aim of spreading chaos among citizens".

The Syrian government meanwhile denied rumours that Assad had fled the city.

Moreover, the interior minister has said there was a "very strong" military cordon around the capital.

But government forces have notably failed to provide any such defence in the cities, towns and villages that have fallen to rebel factions.

Rebel forces led by the Islamist group Hayat Tahrir al-Sham (HTS) have made a lightning advance over the past fortnight after launching a surprise offensive, capturing the north-western cities of Aleppo and Hama before continuing south and entering parts of the strategically important city of Homs.

Their progress has sparked an uprising by allied rebels in the southern region of Daraa, who have taken control of parts of the region.

The UN has said it is withdrawing "non-critical" staff from Syria amid the evolving situation. HTS has pledged to protect international organisations operating in the country.

The UN envoy to Syria has called for an orderly transition of power, as well as "urgent political talks" to implement a Security Council resolution that seeks a negotiated transition between the Syrian government and opposition.

Speaking in Doha on Saturday, Geir Pedersen said representatives of Iran, Russia, Turkey, the US, France, the UK, Germany and the EU had expressed their support for a diplomatic resolution.

Damascus's residents have differing views about a rebel takeover, Ms Shahla said, but are bracing themselves for the possibility of armed conflict on their doorstep.

Her family have remained throughout Syria's civil war, and have not considered fleeing - until now.

While they are not planning on leaving yet, she said, "if things escalate in a dramatic way or a dangerous way, maybe we will think about it".

Additional reporting by Jake Lapham