Russia's Putin, Turkey's Erdogan to discuss Idlib in Moscow

"It's precisely for discussing this complicated situation that the presidents have agreed to have a meeting in Moscow,” Kremlin spokesman Dmitry Peskov said Monday.

A senior Turkish official told Reuters that the meeting, which is due to start at 1:30pm (10:30am GMT), will focus on the security of Turkish soldiers in Syria as one of its main topics.

"We expect Russia to use its influence over the regime on this matter. If there is even the smallest attack on Turkish soldiers, we will retaliate against this," the official told Reuters.

The one-day visit by Erdogan comes as President Bashar al-Assad's forces made advances into the last rebel stronghold of Idlib in Syria's northwest and upped the stakes with Turkey in its months-long offensive backed by Russia.

Turkey is a vocal opponent of Assad and instead backs rebels fighting for his ouster.

Despite being on opposing sides of the Syrian conflict, Ankara last year struck a deal with Moscow to protect the Idlib province from a massive government offensive.

One of Turkey's 12 observation posts set up along the front line between regime forces and anti-Assad rebel and Islamist forces last year were surrounded by Syrian troops this week.

That drew Turkey's wrath, with Foreign Minister Mevlut Cavusoglu saying that Turkish troops would not leave the observation post.

'Mutual efforts'

The announcement of the visit on Friday came shortly after Erdogan and Putin agreed to "activate mutual efforts" to ease the situation in Idlib, according to the Kremlin. 

"They agreed to activate mutual efforts with the goal of liquidating the terrorist threat coming from this region," during a phone call initiated by Erdogan, it said.

According to the Turkish presidency, Erdogan told the Russian leader regime forces' attacks in Idlib "very seriously" threatened Turkey's national security and led to "a grave humanitarian crisis".

"These attacks damage the efforts to regulate the Syrian conflict," it said.

Erdogan is set to host Putin and Iranian counterpart, Hassan Rouhani, for a summit on Syria in Ankara on 16 September.

Iran and Russia are allies of Assad, but work closely with Turkey for a political solution to the conflict. 

The Idlib region is supposed to be protected by the September buffer zone deal but since late April, Syria and Russia have upped their bombardment of the region, which is controlled mainly by Hayat Tahrir al-Sham (HTS), Syria's former Al-Qaeda affiliate.

The lives of three million people in the province are at risk, according to the UN. The April spike in bombardment has killed more than 920 civilians, the Observatory says, and caused more than 400,000 people to flee their homes