Turkey's military fired an artillery round into Syria on Sunday in immediate retaliation after a shell fired from Syria landed in the Turkish border town of Akcakale, broadcasters said, the second such incident in five days.
Prime Minister Tayyip Erdogan warned Syria on Friday that Turkey would not shy away from war if provoked, but a series of mortar bombs fired from Syria have hit Turkey since then.
There were no casualties when the latest Syrian shell hit land near a plant belonging to the Turkish Grain Board (TMO), several hundred metres from the centre of Akcakale, where five civilians were killed on Wednesday in previous Syrian shelling.
The exchanges are the most serious cross-border violence in Syria's conflict, which began as pro-democracy protests, but has evolved into a civil war with sectarian overtones.
NATO member Turkey was once an ally of Syrian President Bashar Assad but turned against him after his violent response to an uprising in which, according to the United
Nations, more than 30,000 people have died.
The Syrian Observatory for Human Rights said the shells fired from Turkey landed near the Syrian town of Tel Abyad.
Broadcaster NTV said the shell from Syria landed in the garden of the TMO plant near storage silos. It said the silos had suffered some damage from shrapnel.
Akcakale had been quiet since Turkey's retaliation on Wednesday and Thursday for the initial shelling, but Syrian government forces began shelling areas around the Syrian town of Tel Abyad on Sunday morning, Dogan news agency reported.
Before the latest strike into Turkey, the Syrian military had fired seven artillery shells on Sunday into an area close to the Syrian customs building, which is around 300 metres from the border and under the control of rebel forces, Dogan said.
People were reportedly killed in those strikes and two Syrians wounded in the strikes were carried through the border fencing and taken to a hospital in Akcakale, Dogan said.
Earlier in the day, a major opposition group warned that Syrian government forces have sent reinforcements to central Homs and could gain complete control of the besieged city.
"The criminal regime has dispatched extra troops to tighten the inhuman siege of the city," the Syrian National Council said in a brief statement.
"Homs' fall will mark a serious turning point in the course of events, subjecting the present and future of Syria as well as the region to great perils."
Opposition rebel forces and troops loyal to President Assad have been fighting in and around Homs for about four months.
The city has been a focal point in the uprising against Assad that began in March last year.
The Syrian Observatory for Human Rights said government troops stepped up their shelling of Homs on Sunday and clashes between troops and rebels taking place inside the city claimed casualties on both sides.
News from Syria cannot be independently verified, as most foreign media are barred from the conflict-torn country.
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