Damascus stirred back to life on Monday at the start of a hopeful but uncertain era after rebels seized the capital and President Bashar al-Assad fled, following 13 years of civil war and more than 50 years of his family's rule.

Heavy traffic returned to the streets and people ventured out after a nighttime curfew, but most shops remained shut.

Rebels milled about in the centre.

The main rebel commander Ahmed al-Sharaa, better known as Abu Mohammed al-Golani, met overnight with Assad's Prime Minister Mohammed Jalali and Vice President Faisal Mekdad to discuss arrangements for a transitional government, a source familiar with the discussions told Reuters.

Al Jazeera television reported that the transitional authority would be headed by Mohamed Al-Bashir, who ran the administration in a small pocket of rebel-held territory before the 12-day lightning offensive that swept into Damascus.

Syria's banks would reopen on Tuesday and staff had been asked to return to offices, according to a Syrian central bank source and two commercial bankers.

Syria's currency would continue to be used, they said.

Fighters from the remote countryside milled about in the capital, clustering in the central Umayyad Square before Damascus's great eight-century mosque.

"We had a purpose and a goal and now we are done with it. We want the state and security forces to be in charge," said Firdous Omar, who said he had been battling the Assad government since 2011 and was now looking forward to laying down his weapon and returning to his job as a farmer in provincial Idlib.

The advance of a militia alliance spearheaded by Hayat Tahrir al-Sham (HTS), a former al Qaeda affiliate, was a generational turning point for the Middle East.

It ends a war that killed hundreds of thousands of people, caused one of the biggest refugee crises of modern times and left cities bombed to rubble, swathes of countryside depopulated and the economy hollowed out by global sanctions. Millions of refugees could finally go home from camps across Turkey, Lebanon and Jordan.

Assad's fall wipes out one of the main bastions from which Iran and Russia wielded power across the region.

Turkey, long aligned with Assad's foes, emerges strengthened, while Israel hailed it as an outcome of its blows to Assad's Iran-backed allies.

The Arab world faces the challenge of reintegrating one of the Middle East's central states, while containing the militant Sunni Islam that underpinned the anti-Assad revolt but has also metastasised into the horrific sectarian violence of Islamic State.

HTS is still designated as a terrorist group by the United Nations, but has spent years trying to soften its image to reassure foreign states and minority groups within Syria.

The group's leader Golani, who spent years in US custody as an insurgent in Iraq but broke with al Qaeda and Islamic State to align his movement with more mainstream anti-Assad groups, has vowed to rebuild Syria.

"A new history, my brothers, is being written in the entire region after this great victory," he told a huge crowd at the Umayyad Mosque in Damascus on Sunday. With hard work Syria would be "a beacon for the Islamic nation".

Assad's prime minister Jalali told Sky New Arabia he was ready to provide documents and assistance for the transfer of power.

The fate of Syria's army would be "left to the brothers who will take over the management of the country's affairs", Jalali said.

"What concerns us today is the continuation of services for Syrians." (Reuters)