Erdogan will pay a one-day visit to Moscow, the presidency said, without giving further details.

The surprise visit comes as the forces of President Bashar al-Assad made advances in the northwest of Syria and upped the stakes with Turkey in its months-long offensive backed by Russia.

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

But Ankara last year struck a deal with Moscow to protect the Idlib province from a massive government offensive.

Turkish officials on Monday "strongly" condemned an air strike on its military convoy heading through Idlib province, saying it was a violation of agreements with Syria.

Ankara blamed "regime forces" for the attack which it said killed three civilians, and the Britain-based Syrian Observatory for Human Rights said the attack was carried out by Syrian and Russian air forces, and was aimed at hindering the convoy's advance through Idlib province.

Putin and Erdogan on Friday agreed to "activate mutual efforts" to ease the situation in Idlib during a phone call, 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.

The Turkish presidency said "ceasefire violations in Idlib by the regime, and its attacks have led to a grave humanitarian crisis."

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

Since late April, Syria and Russia have upped their bombardment of the Idlib region of some three million people, killing more than 860 civilians.