Turkey ‘mows down’ dozens of regime and Hezbollah fighters in northern Syria
Rebel and Turkish fire also killed 10 fighters from Hezbollah, the Lebanese Shia group backed by Iran that is supporting Assad, the Observatory said, adding that Russian strikes killed seven civilians.
Among those killed was Major General Burhan Rahmoun who held a senior position within Syria's Republican Guard, according to a Facebook post by an Al-Akhbar journalist.
There was no confirmation from the Syrian government.
The attacks, which Turkey said targeted more than 200 regime sites in drone and artillery bombardments, were a retaliation to a previous Syrian attack on Turkish forces.
On Thursday, thirty-three Turkish soldiers were killed in an air strike by Russian-backed Syrian regime forces in the Idlib region, the biggest Turkish military loss on the battlefield in recent years.
The latest incident has raised further tensions between Ankara and Moscow, whose relationship has been tested by violations of a 2018 deal to prevent a regime offensive on Idlib.
As part of the agreement, Ankara set up 12 observation posts in the province but Syrian President Bashar al-Assad's forces - backed by Russian air power - have pressed on with a relentless campaign to take back the region.
On Friday, President Recep Tayyip Erdogan spoke by phone with his Russian counterpart, Vladimir Putin, in a bid to scale down the tensions.
However, Erdogan revealed he had adopted a more aggressive tone on Saturday, warning his Russian counterpart to "get out of our way" in Syria's last rebel bastion of Idlib.
"I asked Mr Putin: 'what's your business there? If you establish a base, do so but get out of our way and leave us face to face with the regime,'" he said in Istanbul, recalling his phone conversation.
Depite being on opposite ends, Turkey, which backs several rebel groups in Syria, and key regime ally Russia are trying to find a political solution to the Syria conflict.
Meanwhile, US President Donald Trump condemned the attack on Turkish troops in a call with Erdogan and again urged Russia and Syria to halt the Idlib operation, the White House said.
Secretary of State Mike Pompeo called the attack "despicable and brazen" and said the US was looking at ways to support Turkey, a NATO ally that has recently drifted from the West.
The flare-up raised fresh concerns for civilians caught up in the escalation of the horrific eight-year civil war, with the UN saying nearly a million people - half of them children - have been displaced in the bitter cold by the fighting since December.
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