Kurdish fighters in Syria
Kurdish fighters in Syria Reuters

Dozens of people were killed in Turkish bombardment in Syria on Sunday as Ankara ramped up its unprecedented offensive inside the country against the Islamic State group and Kurdish militants.

The Britain-based Syrian Observatory for Human Rights said at least 40 civilians had been killed in Turkish shelling and air strikes on two areas held by pro-Kurdish forces in northern Syria, the first report of significant civilian casualties in Turkey's operation.

But Ankara said its raids had killed 25 Kurdish "terrorists" and that the army was doing everything to avoid civilian casualties.

The bombardments came after Ankara suffered its first military fatality in the offensive against IS and the Syrian Kurdish People's Protection Units (YPG) militia it launched on Wednesday.

The Observatory said at least 20 civilians were killed and 50 wounded in Turkish artillery fire and air strikes on the village of Jeb el-Kussa early on Sunday.

Another 20 were killed and 25 wounded, many seriously, in Turkish air strikes near the town of Al-Amarneh, it added.

The monitor also said at least four Kurdish fighters had been killed and 15 injured in Turkish bombardment of the two areas.

A spokesman for the local Kurdish administration said 75 civilians had been killed in both villages.

But the Turkish army said it had killed 25 Kurdish "terrorists" from Turkey's outlawed Kurdistan Workers' Party (PKK) and Syria's YPG, state-run Anadolu news agency said.

"All possible measures are being taken to prevent harm to the civilian population living in the area and the maximum sensitivity is being shown on this issue," the army said, quoted by Anadolu.

The Observatory said the bombardment targeted an area south of the former ISIS border stronghold of Jarabulus, which Turkish-led forces captured on the first day of the incursion.

Turkish-backed rebels say they have captured at least nine towns and villages, including Jarabulus, from IS and Kurdish forces since Wednesday.

In a statement Saturday, Kurdish forces accused Ankara of seeking to "expand its occupation" inside Syria.

Funeral for Turkish soldier

The latest fighting is likely to raise deep concerns for Turkey's NATO ally the United States, which supports the YPG as an effective fighting force against ISIS.

Ankara considers the YPG a "terrorist" group and has fiercely opposed its bid to expand into areas recaptured from IS to create a contiguous autonomous zone.

On Saturday, a Turkish soldier was killed and three more wounded in a Kurdish attack south of Jarabulus.

Turkish media named the dead soldier as Ercan Celik, 28, and said a funeral for him would be held on Sunday in Gaziantep, which Turkish President Recep Tayyip Erdogan is currently visiting.

Turkish forces carried out their first air strikes on pro-Kurdish positions on Saturday as part of what Ankara is calling "Operation Euphrates Shield".

Turkey says that the YPG has broken a promise to return across the Euphrates River after advancing west this month, despite US guarantees.

Ankara's military intervention in Syria has added another dimension to the country's complex multi-front war, a devastating conflict that has killed more than 290,000 people and forced millions from their homes since it began in March 2011.

Much of the heaviest fighting this summer has focused on second city Aleppo, which is roughly divided between rebel forces and President Bashar al-Assad's troops.

Push for 48-hour ceasefire

Global powers have been pushing for 48-hour humanitarian ceasefires in the embattled city and UN Syria envoy Staffan de Mistura has urged warring parties to announce by Sunday whether they will commit to a pause in the fighting.

The UN says it has "pre-positioned" aid to go to the city for some 80,000 people.

Russia, which backs Assad's forces, has endorsed the proposal.

But some rebel groups have rejected the plan unless aid passes through opposition-held areas and the ceasefire applies to other areas of Syria under siege.

Opposition groups have repeatedly called for an end to regime sieges of rebel-held areas, accusing Assad's government of using "starve or surrender" tactics.

On Saturday, the last rebel fighters were evacuated from the town of Daraya just outside Damascus, under a deal that followed a brutal four-year government siege.

Hundreds of fighters and their families were bused north into rebel-held territory in Idlib province, with other civilians transferred to government territory near Damascus for resettlement.

The Syrian army said it was in complete control of the town, from which roughly 8,000 civilians were due to be evacuated.