BEIRUT -- Turkey says repeated cease-fire violations by the Syrian government are threatening to derail scheduled peace talks in Kazakhstan.

Speaking to Turkey’s state-run Anadolu news agency on Wednesday, Foreign Minister Mevlut Cavusoglu said Iran needed to address the cease-fire violations in Syria by the government and its allies.

Iran is a key ally of Syrian President Bashar Assad and a guarantor of a tenuous cease-fire agreement that came into force shortly before the new year. Turkey is a sponsor of the Syrian opposition.

The Syrian armed opposition said in a statement on Tuesday that it had decided to put all discussions about the Kazakhstan talks on hold, along with any other consultations regarding the tenuous cease-fire until, in their view, the truce is fully implemented.

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The statement was signed by all the factions who agreed to adhere to the ceasefire agreement brokered by Turkey and Russia with the Syrian regime.

They said their decision to suspend the talks came after Syrian forces and their Iranian-backed allies escalated attacks on the besieged town of Wadi Barada, less than 15 miles northwest of Damascus, where rebels are holed up.

Syrian civil defense sources said Wednesday that six people were killed and 17 more injured in attacks by Iran-backed Hezbollah militants on Wadi Barada during the past three days.

The opposition also cited alleged Russian airstrikes targeting Idlib province and Aleppo’s southern countryside as they suspended involvement in the prelude to the peace talks.

The cease-fire is supposed to prepare the way for talks in Astana, the capital of Kazakhstan, in late January between the government and the opposition. Those talks are to be brokered by Russia, Iran, and Turkey.

Cavusoglu warned the Astana process “might fail if we cannot stop the escalating violations.”