Turkey, Russia and Iran have agreed Friday on the borders of the de-escalation zones, including the main opposition-held region of Idlib, at the Syria peace talks in Kazakh capital Astana, reported Daily Sabah. 

The talks will continue in regard to which forces will be deployed in Idlib, Turkey's official Anadolu Agency quoted diplomatic sources.

A joint statement said that the zones will be formed for a six-month period and will be extended if necessary.

The next round of talks will be held in late October, it added.

The three guarantor states, as well as representatives of the Assad regime and some opposition factions, are meeting in Astana for a sixth round of talks aimed at ending the six-year conflict.

The U.N.'s special envoy on Syria Staffan de Mistura and delegates from Jordan and the U.S. are attending as observers. According to the Kazakhstan Foreign Ministry, Qatar is also participating for the first time as an observer.

Turkey, which supports some opposition groups, and Russia and Iran, which back Bashar Assad's regime, have been holding talks in Kazakhstan since January.

They are seeking to implement lasting cease-fires in areas where fighting has been heaviest between opposition forces and pro-Assad troops.

The parties previously agreed to establish four de-escalation zones, where intense fighting is taking place between the opposition groups and the Assad regime, at the Astana meeting held on May 3-4.

According to a memorandum signed between the parties, the de-escalation zones would include areas in Idlib province and certain parts of the provinces of Latakia, Aleppo and Hama, certain parts of Homs province, eastern Ghouta and Damascus as well as certain parts of Deraa and al-Quneitra.

In addition to the cessation of fighting, the de-escalation deals also include ending flights and air strikes by the regime or U.S.-led anti-Daesh coalition.

At the fifth meeting on July 4-5, it was agreed that the parties would resume work on the borders of the zones.

A separate deal was reached between U.S. and Russia in southern Syrian cities of Deraa and Quneitra, and Russian military police was deployed in the area to monitor the cease-fire which started on July 9.

The Russian Defense Ministry also declared a cease-fire deal in the Damascus suburb of eastern Ghouta.

Russia had also announced a cease-fire deal in Homs, however, the deal was only reached with an opposition group that has limited dominance in the area