Whether or not Iran will be among the nations invited to attend Syrian peace talks in Switzerland is still a source of disagreement between the UN and the United States, peace envoy Lakhdar Brahimi has said.
Speaking at a news conference in Geneva on Friday, Brahimi underlined that Tehran was not completely off the list of those who would attend Geneva 2, despite US objections.
"On Iran, we haven't agreed yet. It's no secret that we in the United Nations welcome the participation of Iran, but our partners in the United States are still not convinced that Iran's participation would be the right thing," Brahimi told reporters after talks with US and Russian officials.
"We have agreed that we will be talking a little bit more to see if we can come to an agreement about this."
Brahimi did announce the 26 nations who were confirmed as attending the talks, due to start on January 22.
Russia, a key ally of the Syrian regime, has sought to have Iran at the table but Reuters news agency reported that a senior US official had said it was "difficult to imagine" Iran at the peace talks.
Brahimi also discussed his concern at the worsening situation in Syria, expressing anger and disappointment at the face that the conflict was still ongoing.
He spoke about the difficulties faced by aid groups seeking access to civilians and criticised both the government for its imprisonment of children and innocent people, and rebel groups for kidnappings.
Brahimi said that the Syrian government had informed the UN that it had formed a delegation for the talks and that its make-up would be made public soon.
Moscow's pointman on the Syria crisis, Deputy Foreign Minister Gennady Gatilov, met Brahimi on Friday and was later quoted by Russian news agencies as saying Foreign Minister Walid Muallem would lead Damascus' delegation.
The opposition, meanwhile, is split between the Syrian National Coalition, which backs the conference, and hardliners who say even talking to President Bashar al-Assad's regime is a betrayal.
"We met representatives of the coalition and they told us they are reaching out to others, inside and outside of Syria," Brahimi said, with the delegation expected to be formed over coming days.
Also on Friday, the head of the rebel Free Syrian Army said he is working to unify rebel ranks.
"The Supreme Military Council [of the FSA] reassures everyone that it is working... with the aim to prevent division [in rebel ranks], to unify ranks and to bring together all the fighters on the ground who believe in the Syrian people's revolution," General Salim Idriss said in a video.
In response to a question from Al Jazeera's diplomatic editor, James Bays, on how representative Geneva 2 would be of those fighting on the ground, Brahimi replied that he hoped the talks "would be as representative as possible" but said this was an ongoing process.