The tomb of Suleyman Shah, the grandfather of the founder of the Ottoman Empire Osman I, on the Euphrates river, is Turkish territory under a 1920s treaty and still guarded by a few dozen Turkish troops.
The pro-government Yeni Safak daily had reported earlier that the 36 Turkish soldiers guarding the tomb had been overwhelmed by a group of some 1,100 IS militants.
It suggested that the troops could now be held hostage by the militants.
"IS militants are now very close to the tomb but our soldiers are still on duty with their equipment," he told reporters in televised comments after a cabinet meeting in Ankara.
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He did not give further details on the condition of the troops.
Turkey, a NATO member, has previously warned that it would consider an attack on Suleyman Shah as an attack on its sovereign territory to which it would respond in kind.
The tomb is located around 25 kilometres south of the Turkish border in northern Syria, much of which is now under the control of IS militants.
The 1921 treaty stipulating the tomb remains Turkish territory was signed between Turkey and France, which was then the colonial power in Syria.
Turkish authorities at the time recognised France's then mandate for control of Syrian territory in return for recognition of its own borders.