ANKARA : The Turkish army blamed the Syrian regime for an air strike on Thursday in northern Syria that killed three soldiers, the first time it has accused Damascus of killing its soldiers since launching its three-month military incursion.

READ MORE: The true north

The incident came on the first anniversary of the shooting down of a Russian military jet over the Syrian border by the Turkish air force. That led to a seven-month crisis in relations between Turkey and Russia, an ally of Syrian President Bashar al-Assad that has provided military support to Damascus.

The army said the strike took place at 3:30 am (0030 GMT) without indicating where in Syria, although local media said it took place in the Al Bab region.

“In the air strike assessed to have been by Syrian regime forces, three of our heroic soldiers were killed and 10 soldiers wounded, one seriously,” the armed forces said in a statement on its website.

Turkish media reported earlier that the attack was by Islamic State (IS) militants.

The prime ministry slapped a broadcasting ban on coverage of the strike an hour after the military’s statement, Turkey’s broadcast watchdog said on its website.

The injured soldiers were taken to hospitals in Turkey’s southeastern cities of Kilis and Gaziantep close to the Syrian border, the official news agency Anadolu said.

The Turkish military launched an operation - dubbed “Euphrates Shield” - with tanks and air power in August to support Syrian opposition fighters seeking to retake territory from IS in northern Syria.

The Ankara-backed rebels comprise several brigades rather than one organised force, according to experts.

Hundreds of Turkish soldiers are taking part in the operation, which President Recep Tayyip Erdogan said this week was pushing forward with its aim of taking Al Bab from IS.

“We reached Al Bab right now and besieged it from the west,” the president said in a speech on Tuesday.

The operation has also targeted Syrian Kurdish militia, whom Turkey views as linked to its outlawed Kurdistan Workers’ Party (PKK), which has staged an insurgency in Turkey since 1984.

The PKK is proscribed as a terror group by Washington and Brussels but not by the United Nations.

“That won’t do. After that (Al Bab), we will go towards Manbij” to remove elements from the Syrian Kurdish Democratic Union Party (PYD) and People’s Protection Forces (YPG) militia, Erdogan said.

Kurdish-led forces recaptured Manbij from IS in August but Ankara has called for them to leave what Turkey emphasises is an Arab majority town.

Erdogan has repeatedly vowed to stop Syrian Kurdish forces from creating an autonomous Kurdish “canton” on Turkey’s southern border, describing it as a “terror corridor”.

Since the offensive began, the rebels captured the IS stronghold of Jarabulus, cleared IS from Al Rai and retook the symbolically important town of Dabiq without much resistance.

The latest deaths raise to at least 15 the number of Turkish soldiers killed since Turkey began its operation in northern Syria.

Most were killed by IS but one soldier died in an attack blamed on the YPG militia.

However, amid the rapprochement with Russia, Turkey has largely been muted as Assad’s forces backed by Moscow press an offensive to recapture the whole city of Aleppo, which is divided between the government and rebels.

The government last week resumed its drive to retake the east of the city, where more than 250,000 civilians have been trapped under siege for months, with dwindling food and fuel supplies.

On Wednesday, the Syrian Observatory for Human Rights, a British-based monitoring group, said dozens of civilians had tried to flee overnight but were forced back by gunfire.

Save the Children called for an internationally monitored ceasefire to allow aid into east Aleppo and the evacuation of sick and wounded civilians.