Assad fled Syria following a lightning offensive spearheaded by Hayat Tahrir al-Sham (HTS) earlier this month.
He left behind a country scarred by decades of “torture, disappearances and summary executions”, and the collapse of his rule on December 8 stunned the world and sparked celebrations around Syria and beyond.
Years of war have also left the country heavily dependent on aid, deeply fragmented and desperate for justice and peace.
Addressing reporters in Damascus, UN special envoy Geir Pedersen said “there is a lot of hope that we can now see the beginning of a new Syria”.
“A new Syria that… will adopt a new constitution… and that we will have free and fair elections when that time comes, after a transitional period,” he added.
Calling for immediate humanitarian assistance, he also stated he hoped to see an end to international sanctions levied against Syria over Assad’s abuses.
UN humanitarian chief Tom Fletcher also called for a massive aid boost by donor countries to respond to “this moment of hope” for Syria.
“Across the country, the needs are huge. Seven in 10 people are needing support right now,” Fletcher told AFP in a telephone interview as he visited Syria.
Pedersen noted a key challenge was the situation in Kurdish-held areas in Syria’s northeast, amid fears of a major escalation between the US-backed, Kurdish-led Syrian Democratic Forces (SDF) and Turkey-backed groups.
Turkey accuses the main component of the SDF, the People’s Protection Units (YPG), of being affiliated with Kurdistan Workers’ Party (PKK) militants at home, whom both Washington and Ankara consider a “terrorist” group.
The United States announced Tuesday it had brokered an extension to a fragile ceasefire in the flashpoint town of Manbij and was seeking a broader understanding with Turkey.
But later on Wednesday, a Syria war monitor claimed 21 pro-Turkey fighters had been killed after they attacked a Kurdish-held position near Manbij despite the ceasefire extension.
Turkish Foreign Minister Hakan Fidan later warned Syria’s new rulers to address the issue of Kurdish forces in the country.
He was responding to a question on Al Jazeera about rumours that Turkey could launch an offensive on the Kurdish-held border town of Kobane, also known as Ain al-Arab.
“There is a new administration in Damascus now. I think, this is primarily their concern now,” he said.
“So, I think if they are going to, if they address this issue properly, so there would be no reason for us to intervene,” Fidan added.
He rejected US President-elect Donald Trump’s claim that the ouster of Assad amounted to an “unfriendly takeover” of Syria by Ankara.
Rooted in Syria’s branch of Al-Qaeda and proscribed as a terrorist organisation by several Western governments, HTS has sought to moderate its rhetoric by assuring protection for the country’s many religious and ethnic minorities.
It has appointed a transitional leadership that will run the country until March 1.
Fidan stressed in his interview that it was time for the international community to take HTS off its terror watchlists.
HTS has vowed justice for the crimes committed under Assad’s rule, including the disappearance of tens of thousands of people into the complex web of detention centres and prisons that was used for decades to silence dissent.
According to the Syrian Observatory for Human Rights, more than 100,000 people died or were killed in custody from 2011.
