Dubai: A deal reached by Russia, Iran and Turkey agreed on Friday to deploy observers on the edge of a “de-escalation” zone in Syria’s Idlib province has been met with criticism by both Syrian regime and opposition groups.

While the deal was hailed as a breakthrough, Fatah Al Sham, formerly the Al Qaida-linked Al Nusra Front, has rejected the deal, pledging to continue the fight.

Fatah Al Sham, which grouped together with other rebel groups to form the Tahrir Al Sham alliance, criticised Free Syrian Army rebels who attended the Astana meetings, which began with Moscow-led diplomatic efforts separate from UN-based peace talks in Geneva.

“We fear the day will come when those factions will line up alongside Russian war planes and fight those who reject Al Assad and his regime,” it said in its statement.

The Syrian regime also criticised the deal viewed as a de-facto partitioning of Syria.

On her part, Bouthaina Shaaban, a senior aide to Al Assad, vowed to take back the entire country, including “Idlib and other areas”.

Syria’s foreign ministry said that Turkish ground troops expected to temporarily monitor a safe zone deal in the country’s northwest as “illegitimate”.

Under the deal, Russian, Iranian and Turkish troops would jointly police Idlib’s ‘de-esclation’ zones.

Al Assad has gained the military upper hand against an array of rebel groups, including some that have received backing from the United States, Turkey and Gulf monarchies.

Damascus views any presence of Turkish forces as illegitimate, Syrian state news agency SANA cited a foreign ministry source as saying on Saturday.

“The deal for Idlib is temporary. Its main goal is reviving the old Damascus-Hama-Aleppo road...and for all kinds of traffic to flow to Aleppo,” the source said.

The government took full control of Aleppo city, east of Idlib, last year in a major blow to rebels.

Critics have described the de-escalation plan as de facto partitioning of Syria after years of multi-sided conflict.

Moscow, Tehran, and Ankara deny this and say the zones will be temporary, although they could extend beyond the initial six-month term.

More than 465,000 people have been killed and millions more displaced since Syria’s crisis erupted in March 2011.