"The Turkish republic is a powerful state and never hesitates to take any measures to protect its national security if need be," Ahmet Davutoglu told AFP in an exclusive interview.

"Any group in Syria, or the regime, should not test Turkey's determination," said the minister, speaking in his central home province of Konya.

Turkey, which backs the three-year-old insurgency against Syrian President Bashar al-Assad and hosts many refugees, on Sunday shot down a Syrian fighter jet inside the Syrian soil, saying that it crossed the border.

The jet was engaged in fighting with al-Qaeda’s al-Nusra Front militants who have been attacking border towns to take control over the Kasab border crossing which is a main supply line for them in the region.

Militants from the radical groups have been entering supplies and forces through Turkish borders.  Syria has long asked the Ankara government to stop flow of arms and foreign militants, but the Turkish government has remained indifferent.

Davutoglu said, "Turkey is ready to take any legitimate step under international law if its national security, including the area where the tomb of Suleyman Shah is situated, is threatened".

Once warm relations between Syria and Turkey have collapsed since the conflict erupted in 2011, with Ankara squarely backing the militants and hosting more than 750,000 refugees, mostly in camps along the border.

Tensions have flared since Sunday's jet downing, which Syria labelled "flagrant aggression".

Fighting at the Syria-Turkey borders has been flared up, and according to military sources, Turkish tanks have been firing artillery at Syrian army bases.

SHI/SHI