Talks got underway between delegations from the three regional power-brokers as well as the Syrian government and opposition, the ministry said in a statement.

In addition to cooling the conflict around the northern province of Idlib -- the last major rebel and jihadist stronghold in Syria -- discussions will focus on creating conditions for the return of refugees and internally displaced people, as well as post-conflict reconstruction, the ministry said.

The United Nations will be represented at the negotiations by Syria envoy Staffan de Mistura, according to the statement, in what will likely be his last engagement on the conflict before leaving the post.

The 10-week-old Idlib truce deal is in the balance after an alleged chemical attack in the government-held city of Aleppo on Saturday, which has triggered retaliatory raids.

The exact circumstances of the attack on three districts of the government-held city remain murky and bitterly disputed.

The Syrian government of Bashar al-Assad has blamed fighters in neighbouring Idlib for the attack, which the Syrian Observatory for Human Rights said hospitalised 94 people.

The incident has put strain on an the already fragile agreement reached in mid-September to fend off a fully-fledged assault on Idlib, which Syria's regime -- backed by Russia and Iran -- has said it is committed to re-taking.

More than half of the region is controlled by Hayat Tahrir al-Sham (HTS), a powerful alliance led by the jihadists of Syria's former Al-Qaeda affiliate, who have not commented on the Aleppo attack.

In September, Russia and rebel backer Turkey agreed to set up a U-shaped buffer zone around Idlib to keep pro-government forces outside the region of some three million.

But on Sunday, Russia said its war planes had carried out their first strikes in the zone since the deal was reached.

Moscow said the raids were a response to the shelling of Aleppo by "terrorist groups" operating inside a part the planned demilitarised area held by HTS.

The negotiations in Astana, expected to conclude on Thursday, are the eleventh of their kind since Moscow began a diplomatic push in early 2017 that effectively sidelined UN-led negotiations on Syria.

The United States has attended some of the Astana rounds as an observer, but US Special Representative for Syria Engagement James Jeffrey said last week that Washington would not attend these talks.

Syria's grinding seven-year civil war has killed more than 360,000 people and displaced millions.