Turkey returned fire after a mortar bomb shot from Syria landed in a field in southern Turkey, on Satruday (local time), the day after Prime Minister Tayyip Erdogan warned Damascus Turkey would not shy away from war if provoked.
It was the fourth day of Turkish strikes in retaliation for mortar bombs and shelling by Syrian forces that killed five Turkish civilians further east on Wednesday.
The strikes and counter-strikes are the most serious cross-border violence in Syria's conflict, which began as a democracy uprising but has evolved into a civil war with sectarian overtones. They highlight how the crisis could destabilise the region.
NATO-member Turkey, once an ally of Syrian President Bashar al-Assad but now a leading voice in calls for him to quit, has nearly 100,000 Syrian refugees in camps on its territory and has allowed rebel leaders sanctuary. Its armed forces are far larger than Syria's.
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 its fire hit Turkey accidentally.
The Hatay governor's office said the round fired from Syria on Saturday landed on empty land near Guvecci village in Yayladagi district, 50 metres inside Turkey, at 7 a.m. (0400 GMT).
"It is assessed that the shell was fired by Syrian Arab Republic security forces at opposition forces along the border," a statement on its website said.
"There was no loss of life in the incident," it said.
"The Guvecci border post retaliated in kind with four rounds from 81 mm mortars."
The Dogan news agency said another mortar round from Syria landed around 50 metres from an observation tower near Guvecci around 11 a.m. (0800 GMT) and smoke rose from the area. There were no immediate reports of casualties or retaliation but a response was expected.
Separately, the governor's office warned people in the area not to go out on balconies or spend time in open places, Dogan said. It said the Red Crescent was offering psychological support to people in the area.
There were two similar incidents in Hatay on Friday.
"Those who attempt to test Turkey's deterrence, its decisiveness, its capacity, I say here they are making a fatal mistake," Erdogan said in a bellicose speech to a crowd in Istanbul on Friday afternoon.
"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," he said.
Turkish artillery bombarded Syrian military targets on Wednesday and Thursday, killing several Syrian soldiers after Syria's initial fatal bombardment.
The United Nations Security Council condemned the original Syrian attack and demanded that such violations of international law stop immediately, while Turkey's parliament authorised cross-border military action in the event of further aggression.
Russia, a staunch ally of Syria, has said it had received assurances from Damascus that the strike on Turkey had been a tragic accident but Erdogan dismissed it, saying this was the eighth time Syrian mortar rounds had hit Turkish soil.
SYRIAN FORCES REPORTEDLY PULL BACK
Wednesday's Syrian strike on the town of Akcakale was of a different magnitude to previous incidents over the past 10 days, a Turkish government official told Reuters, asking not to be identified.
"If there was gunfire, we returned the gunfire, if there was a shell we returned two or three shells, to warn them and deter them. Until Akcakale we were not very concerned that they were deliberate," the official said.
"Wednesday was different. There were five or six rounds into the same place. That's why we responded a couple of times, to warn and deter. To tell the (Syrian) military to leave. We think they've got the message and have pulled back from the area."
Syria has since ordered its warplanes and helicopters not to enter an area within 10 km (six miles) of the Turkish border and told its artillery units not to fire shells in areas close to the border, according to Turkish broadcaster NTV.
Syrian authorities have not confirmed this.
The United States has said it stands by its NATO ally's right to defend itself against aggression spilling over from Syria's war, while Russia appealed to Turkey to stay calm and avoid any action that could increase tensions.
More than 30,000 people have been killed in the revolt against Assad. Rebels said they had captured an air defence base with a cache of missiles outside Damascus on Thursday, a boost to their campaign after a series of setbacks in the capital.
Video posted on YouTube of the aftermath of the assault showed dozens of rebels dressed in army fatigues celebrating as black smoke rose from a military installation behind them.
In the footage, a middle-aged man holding a rifle says the attack was carried out by a rebel battalion from the town of Douma. It also showed rebels at a weapons cache which included what appeared to be part of a surface-to-air missile.
It was not possible to independently verify the videos. Access to Syria for foreign journalists is restricted by the Syrian government.
Although fighting often takes place in the Damascus suburbs, rebel forces have been unable to hold areas for long in the face of government artillery and air power. However, they have staged devastating bomb attacks on government and military offices in the heart of the city.