Syrian armed groups opposed to President Bashar al-Assad have rejected an invitation to UN consultations in Geneva, according to a letter seen by Reuters on Wednesday, dealing an blow to hopes of reviving talks to end the conflict.
The letter from 30 opposition armed groups to the UN Syria envoy Staffan de Mistura, who is presiding over the consultations, accused him of abandoning his neutrality and "standing on the side of one party without the other".
De Mistura's low-key process, which involves him talking separately to scores of interested parties, follows failed attempts by his predecessors to stop the fighting. He was hoping to directly involve the armed groups for the first time.
De Mistura's spokeswoman Jessy Chahine said he had taken note of the letter.
"The consultations continue as usual, and we remain in contact with all relevant parties, including the armed factions, who play an important role in the current Syrian conflict," she said in an emailed comment to Reuters.
The letter to De Mistura said he was biased.
"Your positions and your statements, especially your statement that Bashar al-Assad is part of the solution in Syria, have shown and given us a clear impression of your indifference toward the massacres that the regime is committing," it said.
De Mistura has repeatedly tried to clarify remarks on Assad that he made in February, saying his words was taken out of context and he meant the Syrian president was part of the solution for reducing violence.
The armed groups gave four reasons for rejecting De Mistura's invitation, including "continuing to work with the regime despite its loss of all forms of legitimacy".
They said they would not reject "any real international effort that includes a clear solution" but the UN process "lacked any clear basis or means to get to real outcomes".
De Mistura has said he wants the consultations to enable him to find common ground based on the 2012 Geneva Communique, a document that set out guidelines for ending the violence and launching a political transition.
But the armed groups said the communique "did not refer clearly to the departure of Assad and his regime, with all its symbols and pillars," which it said was the crucial basis for "any supposed solution process".
It also rejected De Mistura's decision to invite Iran to take part in the consultations process, saying it was occupying Syria, trying to undermine its Arab and Islamic identity, violating human rights and committing crimes against humanity.
"We believe that it is the duty of the international community to legally prosecute Iran, not to invite it to meetings and consultative conferences."