Al-Qaeda's Syria affiliate on Saturday rejected the outcome of a Saudi-hosted conference of Syrian opposition figures which agreed to negotiate with the Damascus regime, branding it a "plot".

"It is a plot, not a conference. Such... gatherings must be foiled," Al-Nusra chief Abu Mohamed al-Jolani said in an interview with Orient News, a Dubai-based Syrian opposition television channel monitored in Beirut.

Syria's main political and opposition groups agreed at unprecedented talks on Thursday to negotiate with President Bashar al-Assad's regime, but also insisted that he step down at the start of any political transition