Syrian delegations attending the third day of peace talks in Switzerland are to discuss the release of prisoners, according to the United Nations envoy mediating the sessions.
Lakhdar Brahimi said the two sides would meet on Sunday to talk about those who had lost their freedom during a civil war that has lasted almost three years.
In a news conference in Geneva on Saturday he said: "Prisoners, kidnapped, the nuns from Maaloula, the two bishops, and hundreds, maybe thousands, of people of all ages ... that have disappeared or have been kidnapped. There is this woman, Razan Zeitouneh, and the three people who were with her ... they just disappeared in the vicinity of Damascus.
"All of those people I hope will recover their freedom. But isn’t it a fact that there are thousands and thousands of people in the jails of the government? The United Nations has been calling for the freeing of, at least at the beginning, of women, old people and people underage."
On Sunday, Monzer Akbik, a spokesman for the opposition delegation, said: "We have submitted a list of tens of thousands detainees, including thousands of women and children."
When asked about the detainees of the Free Syrian Army (FSA), he said: "The prisoners in FSA prisons are Prisoners of War. They are fighters not civilians."
Brahimi acknowledged the pace of talks were slow, but played down reports that the government team and the opposition team were either ignoring each other or staging an unofficial boycott.
Key members of the Syrian government delegation - including the foreign minister, Walid Muallem - did not attend the Saturday morning session - and some representatives from the Syrian National Coalition were also missing.
Brahimi said: "I don’t know how you think this is taking place! One delegation is on the left, one is on the right and they face one another and they talk to one another. No, they talk through me to one another. But this is what happens in civilised discussions."
Neither side has issued a formal statement since the talks, called Geneva 2, started on January 22 but people from both delegations have repeatedly briefed the media about their concerns and reservations regarding the process.
On Saturday the two sides talked about the desperate humanitarian situation in the country, especially in Homs.
The peace conference intended to forge a path out of the civil war that has killed 130,000 people has been on the verge of collapse since it was first conceived 18 months ago.
The opposition, which agreed to the peace talks only under intense diplomatic pressure, had been reluctant to sit face-to-face with a government it insists must yield power.
But the government says it is there only to talk about fighting terrorism - the word it uses for its enemies - and that no one can force the president, Bashar al-Assad, to go.