Russia lamented the absence of representatives from the United States at the ninth round of negotiations for a cease-fire in Syria that started in Astana on Monday in search of an agreement to bring an end to the seven-year conflict.

"As you know, they had previously attended, even if it were only at the level of embassy representatives, but this time, unfortunately, the Americans refused to support international efforts to find a solution to the Syrian crisis," the head of the Russian delegation, Alexander Lavrentiev, said.

The Russian envoy for Syria stressed that the absence of US representation at the talks was also regrettable because the way to settle the conflict "can be found only at the negotiating table during an open debate ... and not behind the backs of the Syrian government and the international community."

Lavrentiev also welcomed the arrival in Astana of delegations from the Syrian opposition with whom consultations will be held on Wednesday.

"Tomorrow we will hold substantial negotiations on ways to stabilize the situation not only in Idlib, but also in the rest of Syrian territory," the Russian official said at the end of the first day of talks.

Lavrentiev, who noted a "certain stability" in southern Syria, said that the guarantor states - Russia, Turkey and Iran - will present a final declaration Tuesday with their vision of the situation.

"We are working on the final document that will be presented to the public tomorrow ... so I would avoid going into details," Lavrentiev said.

The Russian official stressed the importance of Astana-9 since the Geneva process "is stagnating."

The previous round of Astana talks on Syria took place last December.

The main achievement of the Astana process has been the creation of four security zones in Syria - in the provinces of Idlib, Homs, Ghouta and on the border with Jordan - territories in which any military activity, including flights, is prohibited.

The current talks in the Kazakh capital are the first since the bombing by the US and its allies of Syrian government targets and the attacks by the Israeli military on Iranian positions in Syria.