Five Turkish soldiers have been killed in an attack carried out by Syrian government forces in Syria's northwest, prompting Ankara to retaliate against dozens of Syrian army targets.

The Turkish defence ministry said Monday's shelling on a military base in Idlib province, the last rebel-held stronghold in the war-torn country, wounded a further five troops.

The "regime's intense artillery fire targeted our elements sent as reinforcement to the region with an aim to prevent clashes in Idlib, ensure our border security and stop migration and human tragedy", the ministry said.

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The Turkish military retaliated by hitting 115 Syrian government targets, according to the ministry, which said it had "neutralised" 101 Syrian military personnel.

Its statement added that the response was carried out "under the rules of engagement and legitimate self-defence".

Turkish authorities often use the word "neutralised" in statements to imply that enemy elements have surrendered, are killed or have been captured.

Al Jazeera's Sinem Koseoglu, reporting earlier from the Bab al-Hawa crossing on the Syrian side of the border, said the Syrian army had targeted the Taftanaz military base, which the Turkish army took over from the Syrian military last week to establish a new observation post.

"This is seen as the highest escalation that has ever happened between Ankara and Damascus in Syria's nine-year war," she said.

"The Turkish armed forces are being hit directly by the Syrian army - and today is a benchmark in this escalation."

Turkish President Recep Tayyip Erdogan and Defence Minister Hulusi Akar held an emergency meeting immediately after the attack, Turkey's NTV television reported.

Ankara has sent major reinforcements to Idlib, as it tries to stem rapid advances by Syrian government forces backed by Russia.

"Their attacks against our posts have made an operation necessary," Omer Celik, spokesman for Erdogan's AK Party, told reporters in Ankara, referring to the Turkish posts set up to descalate tensions in the region.

Russian delegation in Ankara

The Syrian army's assault came after a similar attack by the government forces last week killed eight Turkish military personnel, prompting another response by Turkey's army.

It also happened as a delegation from Russia, the Syrian government's main ally, is in Ankara for talks on the situation in Idlib.

Late on Monday, Ibrahim Kalin, the Turkish presidential spokesman, told the visiting Russian delegation that attacks on observation posts in the region must be stopped immediately, according to Turkey's presidency.

Kalin reportedly stressed that such assaults will not remain unanswered in a two-hour meeting with the Russian officials.

Turkey retaliated against the attack to destroy all enemy targets and avenging our fallen troops.



The war criminal, who ordered today’s heinous attack, targeted the entire international community, not just Turkey. — Fahrettin Altun (@fahrettinaltun) February 10, 2020

Separately, the United Nations said on Monday that nearly 700,000 civilians have been displaced by the latest Syrian government offensive against the rebel-held northwest since early December, including some 100,000 in the past week alone.

David Swanson, a spokesman for the UN Office for the Coordination of Humanitarian Affairs, said the situation was increasingly dire near the border with Turkey, where more than 400,000 people had already taken shelter from earlier anti-rebel offensives last year.

Turkey, which already hosts 3.6 million Syrian refugees, says it cannot absorb any more and has demanded that Damascus pull back in Idlib by the end of the month or face Turkish action.