BEIRUT, Lebanon — Dozens of pro-Syrian government fighters were killed in an assault by Turkish warplanes on the northwestern Syrian region of Afrin on Saturday, according to a local journalist and a militia spokesman.

Fighting has intensified in the region in the past few days, as Turkey has sent reinforcements to press its offensive against towns held by Kurdish groups. Just a day earlier, eight Turkish soldiers were killed, Turkey’s Defense Ministry said in a statement, and more were wounded.

Soldiers loyal to President Bashar al-Assad of Syria had entered Afrin, a Kurdish stronghold, last week to support the Kurdish militia known as the Y.P.G.

Turkey and its allied Syrian rebel fighters say the Y.P.G. is the focus of their operation, which began in January. That has put them at odds with forces loyal to Mr. Assad.