ISTANBUL, Sept. 16 (Xinhua) -- As global and regional powers are wrestling over how best to deal with rebels from their last major stronghold in the Syrian province of Idlib, Turkish analysts warn that a final offensive against the rebel stronghold would risk further deepening divergences between Turkey and Russia.

"The Tehran summit has already amply revealed the differences between Ankara and Moscow over Idlib," said Haldun Solmazturk, a former army general.

Turkish President Recep Tayyip Erdogan's call for a cease-fire in the province was not accepted by Russia or Iran at the tripartite summit in Tehran on Sept. 7.

Days before the meeting, the Syrian and Russian forces began pounding some rebel positions in Idlib in northwestern Syria, drawing criticism from Ankara.

Ankara, Moscow and Tehran are partners in the Astana process aimed at ending clashes and setting the stage for a political settlement in Syria.

Erdogan and Russian President Vladimir Putin are set to meet again on Monday in Russia's Sochi, which indicates that tension is building up over Idlib and things are getting serious, said Solmazturk, who chairs Incek debates at the Ankara-based 21st Century Turkey Institute.

"The failure of the Tehran summit to address the very issue probably marks the end of the Astana process," said Faruk Logoglu, a former Turkish diplomat.

Noting that Moscow turned down Erdogan's proposal for a cease-fire, he said "the gap between Turkish and Russian positions on Syria is therefore likely to continue to widen so long as Moscow backs (Syrian President Bashar) al-Assad and Ankara refuses to talk to al-Assad."

The Syrian army, backed by the Russian air force and Iran-linked militia, is preparing to launch an all-out offensive to wipe out the rebels from their last major stronghold in Idlib.

Remarks made by top Turkish officials in the wake of the Tehran summit suggested that Ankara would not remain silent in case the Syrian army launches a full-scale attack on Idlib.

Erdogan cautioned at the summit that it was vitally important to maintain Idlib's current status as a de-escalation zone. A Syrian offensive would collapse the ongoing Astana process.

In Solmazturk's view, Erdogan would try to talk Putin out of launching an offensive against the Idlib rebels at the Sochi summit.

"It's more probable that Putin would persuade Erdogan," he said, arguing that Putin would not have flatly rejected Erdogan's proposal for a cease-fire if Moscow were not determined to eliminate the terrorism threat in Idlib.

Both Russia and Iran are aware that Erdogan sees eye to eye with the United States over a medium-term game plan in Syria, said Solmazturk.

Moscow and Tehran have been staunch supporters of Damascus in the war, while Ankara backed, together with the U.S., the rebels in efforts to topple the al-Assad government.

"Ankara must understand that Idlib is a Syrian territory and the best path to follow is to help restore Syrian sovereignty there without harm to civilians and without a bloodbath," said Logoglu.

"This requires getting in touch with the Syrian government," he added.

Ankara has so far refused to officially get in touch with the Syrian government on the grounds that it is killing its own people.

Turkey favors a political solution in Idlib, in which Ankara-backed so-called moderate rebels in the region should be spared from any attacks.

The al-Qaida-linked Hayat Tahrir al-Sham alliance controls much of the Idlib province, while Ankara-backed rebels hold the rest of the territory.

"All in all, if Ankara persists in its present course, it will be painting itself into a corner and face increased isolation in Syria," said Logoglu.

Based on a deal concluded last year with Moscow and Tehran as part of the Astana process, the Turkish military has set up a total of 12 observation posts in Idlib, which have been reinforced with tanks and artillery since last week, according to media reports.

A commander of the Turkey-backed Free Syrian Army claimed in the past week that Ankara told them the Turkish military would not withdraw from the observation posts and they would be supplied with weapons and ammunition in case of a Syrian offensive.

Solmazturk does not expect, however, that the divergences of opinion would lead to a Turkish military confrontation either with Moscow or with the Syrian army on the ground.

"It's not possible to rule out such a possibility, but it's very unlikely," he said. "I don't think neither Turkey, nor Russia nor Syria could afford to take such a risk. All the three parties would carefully avoid that."

Ibrahim Kalin, Turkish presidential spokesman, had argued that the presence of Turkish soldiers in Idlib was probably the only guarantee to prevent any major assault.

"Because the Russian jet fighters and the regime ground forces cannot afford attacks while Turkish soldiers are there," he said about a week ago.?