The Turkish military returned fire after a mortar bomb shot from Syria landed in countryside in southern Turkey on Saturday, the state-run Anatolian news agency reported.

It was the latest in a series of Turkish retaliatory attacks in response to mortar bombs and shelling by Syrian forces that have killed five Turkish civilians further east along the border.

The strikes and counter-strikes have been the most serious cross-border violence seen so far in Syria's conflict, and underlined how it could destabilize the region.

Turkish Prime Minister Tayyip Erdogan said on Friday his country did not want war but warned Syria not to make a "fatal mistake" by testing its resolve. Damascus has said the mortars landed in Turkey accidentally.

Anatolian said the mortar round hit countryside near Guvecci village in the Yayladagi area amid intense clashes on the Syrian side of the border in Idlib province.

"Military units on the Turkish border launched retaliatory fire immediately," the agency said, without identifying its source or mentioning any casualties.

In a belligerent speech to a crowd in Istanbul on Friday, Erdogan had warned Syrian President Bashar al-Assad that Turkey would not shy away from war if provoked.

The speech followed a Syrian mortar barrage on a town in southeast Turkey that killed five people on Wednesday.

Turkish artillery bombarded Syrian military targets on Wednesday and Thursday in response, killing several Syrian soldiers, and the Turkish parliament authorized cross-border military action in the event of further aggression.

"We are not interested in war, but we're not far from war either. This nation has come to where it is today having gone through intercontinental wars," Erdogan said in his speech.

"Those who attempt to test Turkey's deterrence, its decisiveness, its capacity, I say here they are making a fatal mistake."

At least two mortar bombs fired from Syria landed in farmland in Turkey's southern Hatay province on Friday, one of them around 50 meters into Turkish territory, and a military unit responded immediately, Hatay Governor Celalettin Lekesiz was quoted as saying by the state-run Anatolian news agency.-Reuters