Talks between Syria's delegations in Geneva entered their sixth day Thursday with discussions set to focus on "terrorism", both sides said.
Delegations from Syrian government and the opposition coalition sat down from around 10:45 am , the UN said.
The morning session would be dedicated to discussing violence on the ground and the fight against "terrorism", both sides said, although they disagreed on what that implied.
The Government delegation has long insisted the talks need to address "terrorism" by jihadists and armed groups in the opposition, whom it blames for most of the bloodshed in the country.
As meetings got under way last week, Syrian officials brandished what they said was a list of militants "terrorism" and lambasted countries such as the Arab monarchies and Turkey which are key opposition supporters.
U.N mediator "Lakhdar Brahimi" said that "despite the combative tone, relations between the two sides appeared to be thawing". He told reporters Wednesday "the ice is breaking, slowly, but it is breaking".
He acknowledged he did not expect "anything substantive" to come out of the initial round, which is set to conclude Friday. But he stressed that simply getting the parties talking for the first time since the conflict erupted in March 2011 was an important step.
The two sides have been brought together in Geneva in the biggest diplomatic push yet to end a crisis that has left more than 130,000 dead and forced millions from their homes.
Brahimi said they were set to decide on the last day of the talks on Friday when they would return to Geneva for a second round, likely after a week, adding "I hope that the second session will be more structured and hopefully more productive than the first session".
Syrian government delegation member "Buthaina Shaaban" said "we wanted "to discuss Geneva-I item by item, pointing out that the first point in the text calls for ending the violence, which it largely equates to rooting out "terrorism".
Brahimi acknowledged Wednesday that "the gap between the two sides is quite large" and called on the United States and Russia to "use their influence".
No progress was meanwhile apparent towards fulfilling the only tangible promise of the Geneva talks so far: the Government's promise to allow women and children safe passage from Homs, where an estimated 3,000 people living with the barest of supplies.
U.N bodies and the International Committee of the Red Cross have said they are on standby with aid but are waiting for approval to move in.