Turkey has sent a convoy of armored vehicles and commando units to the southern province of Hatay on the Syrian border, Anadolu Agency (AA) said on Friday.

The convoy would be sent to reinforce Turkish military presence on the border near the northern Syrian province of Idlib, the last major opposition stronghold in Syria.

The convoy had reached Hatay's Yayladağı region, from where it moved toward the units on the border, AA said. A Turkish security source said that the Turkish military had been rotating forces in and out of the region, but declined to say whether the latest movement was in preparation for an operation inside Idlib itself.

Maria Zakharova, a spokeswoman for Russia's Ministry of Foreign Affairs, said Friday that Russia remained committed to an agreement it had struck with Turkey to stabilize a de-escalation zone in Syria's Idlib province, but said Moscow was worried by an increase in the number of cease-fire violations there.

President Recep Tayyip Erdoğan and Russian President Vladimir Putin agreed in September 2018, following their talks in Sochi, to establish a demilitarized zone in Idlib in order to decrease tension and prevent a new conflict in the province. According to the 10-article memorandum signed between Ankara and Moscow during the meeting, the Idlib de-escalation area will be preserved, and Turkish observation posts will be fortified and continue to function.

Russia will also take all necessary measures to ensure that military operations and attacks on Idlib are avoided, and the existing status quo is maintained. The agreement also envisaged the removal of "all radical terrorist groups" from the demilitarized zone by October 2019.