ANKARA: Turkey announced Friday it had deployed dozens of soldiers in the Syrian province of Idlib as part of its efforts to establish a de-escalation zone to stop fighting in the largely jihadist-controlled northwestern region.

The deployment also appeared to be aimed at preventing the expansion of Syrian Kurdish militia backed by the United States, but considered by Ankara to be "terrorists".

Over 100 soldiers, including special forces, and 30 armoured vehicles entered Idlib, Turkey's Hurriyet daily reported on Friday, as it speculated more troops could be sent to the province over the next few days.

In a statement on Friday the military said that it had begun "activities to establish observation posts on October 12 (Thursday)".

President Recep Tayyip Erdogan said on Friday that Turkish armed forces had entered Syria with the Free Syrian Army, the name Ankara uses when referring to rebels seeking President Bashar al-Assad's ouster.

"We said we would come unexpectedly in the night, and last night... we started the operation," he said during a televised speech in Ankara.

"No one can say to us, 'why are you doing this'?" he thundered.

Idlib is largely controlled by Hayat Tahrir al-Sham (HTS), a group led by Al-Qaeda's former Syria affiliate, which ousted more moderate rebels in recent months.

The latest deployment comes after the Turkish army launched a reconnaissance mission on Sunday as part of efforts by Turkey, along with Russia and Iran, to set up the zone in line with accords in Astana peace talks aimed at ending the Syrian civil war.

Turkey says it is backing Syrian rebels in a bid to oust HTS members in the area to allow Iranian, Russian and Turkish forces to implement the zone.

They agreed on four such ceasefire zones in Syria as a prelude to negotiations.

500 soldiers

Three zones are already in place -- in Eastern Ghouta near Damascus, in central Homs, and in parts of southern Syria -- which are being monitored by Russian military police.

The fourth de-escalation zone includes Idlib but also parts of the neighbouring Latakia, Hama and Aleppo regions.

The Britain-based Syrian Observatory for Human Rights confirmed late Thursday a Turkish military convoy entered Idlib before heading towards the western part of Aleppo province.

The operation's target is the HTS but Observatory head Rami Abdel Rahman told AFP in Beirut that Turkish forces were escorted by HTS elements, appearing to suggest a degree of coordination by Turkey with the group.

A total of 14 "observation posts" will be set up by the Turkish army, according to local media, while some 500 Turkish soldiers could be deployed to Idlib.

While Turkey supports Syrian opposition fighters and calls for Assad's ouster, Ankara has worked closely in the last few months with Russia -- who supports Assad -- in the hope of bringing the war to an end.

Idlib is one of the last remaining strongholds of the rebels, which has recaptured vast swathes of territory from opposition fighters since Moscow intervened on its behalf in September 2015.

The Syrian conflict began after widespread protests against the government in 2011 but has since turned into a multi-front war that has killed more than 330,000 people.

Ignite another war

The last time Turkish forces were engaged in Syria was in August, when Turkey launched its eight-month long Euphrates Shield operation against jihadists and Kurdish militia in northern Syria.

One of Turkey's main concerns is the expansion of the Syrian Kurdish People's Protection Units (YPG), which Ankara says is linked to the Kurdistan Workers' Party (PKK) waging an insurgency inside Turkey.

Erdogan has repeatedly vowed he will not allow the YPG to form a "terror corridor" reaching the Mediterranean on Turkey's southern border.

Moustafa Sejari, a senior official in rebel group Liwa al-Moutassem taking part in the operation, said on Twitter that the Turkish deployment was intended to "protect the region from bombing and to cut the path of (Kurdish) separatists".

The YPG accused Turkey of making threatening moves towards Afrin, the neighbouring region held by the militia.

"Turkey is not after anything in Idlib but (an) Afrin siege could ignite fire of another war in the region," the YPG said on Twitter.—AFP