Nineteen Islamist groups fighting to topple President Bashar al-Assad have rejected outright a mooted US-Russian peace initiative for Syria dubbed Geneva 2, a statement said.
"We announce that the Geneva 2 conference is not, nor will it ever be our people's choice or our revolution's demand," the groups said in a late Saturday statement read in an online video by Ahmad Eissa al-Sheikh, chief of the Suqur al-Sham chief.
"We consider it just another part of the conspiracy to throw our revolution off track and to abort it."
The statement also warned that anyone who went to such talks would be committing "treason, and ... would have to answer for it before our courts".
The statement comes weeks after dozens of major rebel groups across Syria said the Western-backed opposition umbrella grouping the National Coalition had "failed".
The Geneva talks slated for next month aim to bring rebel and regime representatives to the table in a bid to seek a negotiated end to the Syrian conflict, which according to a rights group has claimed more than 115,000 lives since it erupted in March 2011.
The National Coalition is to meet on November 9 to decide whether to take part in the peace talks but has stated emphatically it will only attend if there are guarantees they Assad will step down.
Assad for his part has said "the factors are not yet in place" for such talks, and he has repeatedly rejected negotiations with any group with ties to the rebels or to foreign states.
Among the signatories to Saturday's statement are powerful Islamist groups Liwa al-Tawhid, Ahrar al-Sham, Suqur al-Sham and Ahfad al-Rasul, which has fought against Al-Qaeda-affiliated fighters in Syria.