A Turkish soldier has been killed during action in Syria, the first military Turkish fatality in Ankara's cross-border offensive, now into its third day.

The Turkish defence ministry said on Friday that three soldiers were wounded, without providing details.

Separately, the ministry said 49 more "terrorists" were "neutralised" in the incursion, in reference to Syrian Kurdish fighters.

It said the total number of Kurdish fighters killed in the incursion now numbers 277.

Those numbers could not be independently verified.

READ MORE: Pictures: Refugees flee as Turks press further in to Syria

Turkey considers the Syrian Kurdish fighters terrorists linked to a Kurdish insurgency within Turkey and has launched an invasion into northeastern Syria this week.

Ankara says the offensive is necessary for national security.

There have been civilian casualties on both sides: six civilians in Turkey and seven in Syria.