Syria's largest opposition coalition on Wednesday named an Islamist rebel chief backed by Riyadh as its chief negotiator for peace talks slated to open on January 25 in Geneva.
The coalition of political and armed opposition groups demanded the exclusion of other parties from the talks and a halt to the Syrian army's bombardment and sieges of populated areas.
It has appointed Mohammed Alloush, a political leader of the Saudi-backed armed group Jaish al-Islam, as its chief negotiator, the coalition's general coordinator, Riad Hijab, announced at a news conference in Riyadh.
He said Asaad al-Zoabi, a general who defected from the army, will serve as head of the delegation, with Syrian National Council chief George Sabra as his deputy.
A 33-member opposition "supreme committee" was formed at a landmark meeting last month of Syrian opposition groups in the Saudi capital.
Hijab insisted the committee's delegation should be the only opposition representative at the talks, aimed at bringing an end to a five-year-conflict that has cost more than 260,000 lives.
"We will not go to negotiations if a third party or person is added," he warned.
Hijab also said that "we cannot go to negotiations with our people dying of hunger and under shelling" by pro-regime forces.
Countries pushing for a peace deal for Syria, including the United States, Russia, Saudi Arabia and Iran, have struggled to agree on the list of opposition delegates.
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Russia and Iran, Saudi Arabia's regional rival, are the main supporters of President Bashar al-Assad. Moscow wants the participation of Damascus-tolerated opposition groups.
Saudi Foreign Minister Adel al-Jubeir said Tuesday that the Riyadh-based committee was "the concerned body, and nobody else can impose on them who should represent them" in negotiations.
Riyadh in December brought together about 100 representatives at the meeting of Syria's main political opposition and armed factions.
They agreed to negotiate with the regime but insisted Assad step down at the start of any political transition.
The Islamic State jihadist group, which has seized large parts of Syria and Iraq, and the Al-Qaeda affiliated Al-Nusra Front were excluded from the Riyadh meeting.
Kurdish fighters were also left out.
A newly formed secular Kurdish-Arab alliance, the Syrian Democratic Council, last week demanded its own seat at the negotiating table and said it would not be grouped with the Riyadh body.
Syria's tolerated domestic opposition, the National Coordinating Committee for Democratic Change, belongs to the Riyadh grouping but on Wednesday slammed Alloush and Zoabi's appointments.
It said it was "not acceptable for the head of the delegation and the chief negotiator to be affiliated with the armed opposition" and urged the make-up of the delegation be changed.
"This sends the wrong political message to the Syrian people," the NCCDC added in a statement from Damascus.