Syrian peace talks being sponsored by the United Nations have resumed in Geneva, 10 months after they fell apart over escalating bloodshed in the war-torn country.
UN Syria envoy Staffan de Mistura convened his first meeting with the delegation of the Syrian government, headed by Bashar al-Ja'aafari.
He later met with the head of the opposition delegation in Geneva, Yahya Kadamani, and Nasr Hariri, a senior member of the largest opposition group, the Syrian National Coalition.
The talks are the latest bid to end the country's six-year war that has killed hundreds of thousands of people and displaced millions more.
The Geneva talks come after ceasefire discussions in Astana, Kazakhstan, that were coordinated largely by Turkey and Russia, which have backed opposite sides in the war.
In those meetings, the two sides sat face-to-face and a fragile ceasefire has since mostly been holding, though violations occur daily.
Assad's forces were able to expel rebel fighters in December from a long-time stronghold on the eastern side of the city of Aleppo, which was Syria's economic capital and largest city before the war began.
Speaking ahead of the Geneva meeting, an opposition delegation spokesman said that they hoped to achieve "at least something at the human dimension: lifting the siege in certain areas, getting aid to those who are besieged".
He also hoped there would be serious work on the issue of political transition, a sticking point of past talks.
"The world has to end this saga. The world has to end these brutalities," said Yahya al-Aridi.
This is the fourth round of negotiations since early last year.
Meanwhile, Turkey's state-run news agency said Turkish troops and allied Syrian fighters have seized the centre of the town of al-Bab from the Islamic State group.
Anadolu Agency, quoting Syrian opposition force commander Ahmed al Shahabi, said the troops were clearing mines and other explosives left behind by the IS militants.
Turkey sent troops across the border into northern Syrian in August to help Syrian opposition forces battle IS and halt the advances of US-backed Syrian Kurdish fighters.
The troops had become bogged down in a gruelling battle over al-Bab, one of the few remaining IS strongholds in northern Syria.
On Wednesday, Mr de Mistura played down expectations for the talks, saying he did not expect any breakthroughs.
Abdulahad Astepho, a member of the opposition delegation, said rebels would feature in a "greater role" in this round of talks, reflecting the changing dynamics inside Syria, where factions are drifting away from the exiled opposition leadership and closer to ultraconservative groups such as Ahrar al-Sham and the al Qaida-linked Fatah al-Sham Front.
On Thursday, activists reported heavy clashes across the southern city of Daraa between pro-government forces and opposition factions headed by an al Qaida-linked group.
Opposition media agencies also reported government air raids around the Hama countryside, in central Syria.
The government has insisted that the ceasefire does not protect al Qaida-linked groups, while rebels say the agreement they signed in Ankara says it does.
Rebels have found themselves dependent on al Qaida's battle-hardened factions since 2015 to rebuff government advances around the country.
The Syrian government has repeatedly denounced Turkey's troop presence as a violation of Syrian sovereignty and an act of aggression, but the two sides have not faced off.
Government forces are instead focusing their efforts on forcing out the opposition from positions around the capital, Damascus, and fighting rebels in Daraa, and the Islamic State group in the north and east of the country.
Mr de Mistura also met with a group of Syrian women who came to push for the discussion of the fate of detainees and abducted people in the Syrian conflict.
They held a symbolic moment of silence together.
"There are thousands and thousands of mothers, wives, daughters who are hoping that at least this aspect will be one of the benefits of any negotiation," he said.