The Syrian government has accused Turkey of failing to meet obligations set out in an agreement with Russia to create a demilitarised zone free of jihadists in the northwest, at odds with the Russian view that Ankara is fulfilling the deal.
The agreement forged in September between Russia, President Bashar al-Assad's most powerful ally, and Turkey, which backs the rebels, staved off a major government offensive into the opposition-held Idlib region.
Russian President Vladimir Putin said on Saturday that Ankara was fulfilling its obligations in Idlib.
But Syrian Foreign Minister Walid al-Moualem said in comments reported late on Monday that Turkey appeared unwilling to implement the deal.
"The terrorists still exist with their heavy arms in this region and this is an indicator of Turkey's unwillingness to fulfill its obligations," Moualem said in Damascus, according to the official news agency SANA.
The Syrian government has vowed to recover "every inch" of Syria, including the Idlib region.
The Turkish-Russian agreement established a buffer zone running 15-20 km (9-13 miles) deep into rebel territory that was to be free of heavy weapons and jihadists by mid October.
The main jihadist group in the northwest, Tahrir al-Sham, gave a nod of approval to the Turkish agreement, but without explicitly saying it would abide by it.
Idlib and adjacent areas are the last stronghold of the anti-Assad insurgency.
Turkey has established 12 military positions in the northwest under a previous agreement with Russia and Iran, Assad's other main ally.
The United Nations warned that any major offensive into the Idlib region would cause a humanitarian catastrophe. The region is home to around 3 million people.