UN Secretary-General Ban Ki-moon has met with Russian Foreign Minister Sergei Lavrov in the southern Russian city of Sochi for talks centered on the crisis in Syria.
At a press conference following their meeting, Ban said it is crucial not to lose momentum in the process of responding to the crisis and that he supports a recent joint call by Lavrov and U.S. Secretary of State John Kerry to convene an international conference on the matter.
He added that this must be done as soon as possible.
Lavrov said it is important that Syrians decide for themselves who will represent the conflicting sides.
"Now the most important is to understand who from the Syrian sides is ready to participate in this conference," he said. "Without that, nothing will happen. And the second task is to determine the circle of participants among countries other than Syria."
He said, however, that no "terrorists" should be invited.
"I wouldn't exclude anyone. With the exception of those who are not really opposition activists, but more like terrorists," Lavrov said. "The Nusra Front is a well-known structure which the Americans put on the terrorist list. Its leaders openly say that they receive orders from Al-Qaeda. There are also other terrorist groups. Of course, they should not be part of the dialogue.
"We are talking about the political opposition, even the armed opposition -- while understanding at the same time that terrorists have no place at the negotiating table."
Lavrov also said all of Syria's neighbors should attend any peace conference, including Iran.
"Iran has repeatedly underlined its solidarity with the Syrian government," he said. "Iranian officials pay regular visits to Damascus, so there is no doubt about that. I'd like to stress once again that no geopolitical bias should be an obstacle to Iran taking part in preparing for and holding the conference [on Syria] from the very beginning."
Ban and Lavrov both repeated calls for a UN-led investigation into charges that chemical weapons have been used in Syria.
Ban wants a UN team to be allowed to assess allegations that such weapons were used near the city of Aleppo.
"It is regrettable that this investigation team has not been able to visit and enter Syria to have an on-site investigation, an assessment of the situation," Ban said. "Nothing can replace, in terms of effectiveness, this on-site investigation."
Lavrov said the government of Syrian President Bashar al-Assad has indicated it will allow international inspectors to investigate the claims.
Ban and Lavrov also discussed other pressing international issues, including the Middle East peace process, the situation in Afghanistan, and tensions on the Korean Peninsula.
Ban is also meeting with Russian President Vladimir Putin.