The Syrian opposition's main political body has urged rebel groups to co-operate with "sincere regional efforts" to reach a ceasefire deal but that it had not been invited to any conference, referring to a meeting in Kazakhstan proposed by Russia.
Riad Hijab, general co-ordinator for the High Negotiations Committee, said confidence-building measures were needed to create an atmosphere for political transition talks which should be held in Geneva and sponsored by the United Nations.
Russia's foreign minister on Tuesday said the Syrian government was consulting with the opposition ahead of possible peace talks.
In an interview with Interfax news agency, Sergei Lavrov did not say where the consultations were taking place or which opposition groups were taking part.
Russia, Iran and Turkey said last week they were ready to help broker a peace deal after holding talks in Moscow where they adopted a declaration setting out the principles any agreement should adhere to.
Arrangements for the talks, which would not include the United States and be distinct from separate intermittent UN-brokered negotiations, remain hazy, but Moscow has said they would take place in Kazakhstan, a close ally.
"During the recent meeting in Moscow with my colleagues from Iran and Turkey we approved a joint declaration in which we confirmed our readiness to guarantee a future agreement between the Syrian government and the opposition," Lavrov told the Interfax news agency in an interview.
