Armed opposition groups in Syria have said that they will not attend the Geneva II peace talks, saying that negotiating with the government of Bashar al-Assad would be an act of betrayal.
The powerful opposition group's statement comes on Sunday as fighting rages on near the border with neighbouring Iraq and in the central city of Homs.
The Geneva peace talks set to take place on November 23 have been repeatedly postponed amid wrangling among the Syrian opposition, and a dispute over which countries, including Iran, should participate.
Meanwhile, in a hopeful turn, Assad's government has handed over on time a detailed plan on destroying its chemical weapons stockpile, an international watchdog has said.
A move in line with US-Russian deal reached last month that headed off threatened military strikes on Syria and triggered the initiative for peace talks staged in Switzerland next month.
However, in the latest blow to the peace talks, 19 of the groups fighting to topple Assad issued a statement saying: "We announce that the Geneva II conference is not, nor will it ever be our people's choice or our revolution's demand."
The statement was read out by Suqur al-Sham brigade chief Ahmad Eissa al-Sheikh in a video posted online.
"We consider it just another part of the conspiracy to throw our revolution off track and to abort it."
They warned anyone who attends such talks would be committing "treason, and... would have to answer for it before our courts".
Iran's President Hassan Rouhani also weighed in on the upcoming talks, saying that part of the solution to the Syria crisis was expelling 'terrorist groups' from the country and complete the destruction of chemical weapons, a report said.
"Iran believes [in]... preventing the entry (and) expelling terrorist groups from Syria and the complete destruction of chemical weapons will be first important steps for achieving stable peace in Syria," Rouhani said in comments reported by the official IRNA news agency.
The statement comes as the UN-Arab League peace envoy to Syria, Lakhdar Brahimi, prepares to travel to Damascus on Monday garnering support for the upcoming talks, a Syrian government source told AFP news agency.