File photo: Smoke billows following Turkish bombardment on Syria s northeastern town of Ras al-Ain in the Hasakeh province along the Turkish border on October 9, 2019. AFP
The strikes mostly targeted Kurdish-held Tal Rifaat and Manbij in the country's north near the Turkish border, areas Ankara has repeatedly threatened to attack.
"Turkey has significantly escalated its drone strikes since the start of the week," with 16 killed on Wednesday alone, said Rami Abdel Rahman, who heads the Syrian Observatory for Human Rights war monitor.
The Turkish defence ministry meanwhile said its forces had "destroyed terrorist targets" and "neutralised 16 terrorists", referring to Kurdish-led fighters.
Four fighters from the Kurdish-led Syrian Democratic Forces (SDF) were killed when "a Turkish drone targeted a military vehicle" in Hasakeh province, which is run by a semi-autonomous Kurdish administration, the Britain-based Observatory said.
The US-backed SDF is the Kurdish administration's de facto army, and its fighters spearheaded the battle against the Islamic State group in Syria, driving it from its last stronghold in the country in 2019.
Turkish drone strikes in northern Syria's Aleppo province killed six fighters from the Manbij Military Council, which is affiliated with the SDF, according to a statement from the council.
Four were killed as they were trying to transport children who were wounded in a ground attack to hospital, the Observatory said.
One civilian working for the Kurdish administration was also killed in a strike in the Manbij area, added the Observatory, which relies on a wide network of sources on the ground in Syria.
In the mostly Kurdish-held Tal Rifaat enclave, five Syrian soldiers died following "a Turkish drone strike on a regime military position", according to the war monitor.
The enclave has Turkish-controlled areas to its north and regime-held territory to its south.
Syrian state media did not immediately report the incident.
Ankara has launched successive military offensives in Syria, most of them targeting Kurdish militants that Ankara links to a group waging a decades-long insurgency against the Turkish state.
Turkey stepped up deadly drone strikes in Kurdish-controlled parts of Syria after a July 2022 summit with Iran and Russia failed to provide Ankara with a green-light for a fresh offensive, mainly on Tal Rifaat and Manbij, Kurdish officials and the Observatory said at the time.
Since Syria's war erupted in 2011 with the brutal repression of peaceful protests, the conflict -- which has drawn in foreign powers and global jihadists -- has killed more than 500,000 people and displaced millions.