Turkey-backed Syrian opposition fighters seized a number of villages and towns from Kurdish-led militias in northern Syria on Sunday amid Turkish airstrikes and shelling that killed at least 35 people according to opposition and a monitoring group.

Turkey sent tanks across the border to help Syrian opposition fighters drive the ISIS group out of the frontier town of Jarablus last week in a dramatic escalation of its involvement in the Syrian civil war.

The operation, labeled Euphrates Shield, is also aimed at pushing back US-allied Kurdish forces.

Turkey's official Anadolu news agency said Turkish airstrikes killed 25 Kurdish "terrorists" and destroyed five buildings used by the fighters in response to attacks on advancing Turkish-backed opposition fighters in the Jarablus area.

The Turkish military is "taking every precaution and showing maximum sensitivity to ensure that civilians living in the area are not harmed," Anadolu reported.

A Turkish soldier was killed by a Kurdish rocket attack late Saturday, the first such fatality in the offensive, now in its fifth day.

The SDF crossed the Euphrates River and drove ISIS out of Manbij, a key supply hub just south of Jarablus, earlier this month. Both Turkey and the United States have ordered the YPG to withdraw to the east bank of the river.

YPG leaders say they have, but their units play an advisory role to the SDF and it is not clear if any of their forces remain west of the Euphrates.
ANHA, the news agency of the Kurdish semi-autonomous areas, said Beir Khoussa has "reportedly lost all its residents."

SDF spokesman Shervan Darwish said the airstrikes and shelling started overnight and continued Sunday along the front line, killing many civilians in Beir Khoussa and nearby areas. He said the bombing also targeted Amarneh village. He said 50 Turkish tanks were taking part in the offensive.

An Associated Press reporter in the Turkish border town of Karkamis spotted at least three Turkish jets flying into Syria amid heavy Turkish shelling from inside Syrian territory on Sunday morning.

(Additional editing by Al Arabiya English)