* Ankara says Ottoman tomb in Syria is Turkish territory
* Islamist militants hold area where tomb is located
ISTANBUL, March 14 (Reuters) - Turkey threatened on Friday to retaliate for any attack on the tomb of Suleyman Shah, grandfather of the founder of the Ottoman Empire, in an area of northern Syria largely controlled by militant Islamists.
Ankara regards the tomb of Suleyman Shah as sovereign Turkish territory under a treaty signed with France in 1921, when Syria was under French rule. About two dozen Turkish special forces soldiers permanently guard the tomb.
The Turkish warning follows clashes this week between militants of the Islamic State of Iraq and the Levant (ISIL), an al Qaeda breakaway group, and rival rebel groups in the area of the tomb, which lies east of Aleppo near the Turkish border.
ISIL and other militants, whose strict Salafi interpretation of Islam deems the veneration of tombs to be idolatrous, have destroyed several tombs and mosques in rebel-held areas.
"Any kind of attack ... will bring retaliation. In defending its sovereign territory, Turkey will take all measures necessary without any hesitation," Foreign Minister Ahmet Davutoglu told a televised news conference.
"At the current time there is no question of any intrusion targeting our territory and our soldiers, but we stand ready to take whatever steps are needed in the event of a threat. The Turkish public need have no doubts in this regard," he said.
Davutoglu, who was speaking in the eastern Turkish city of Van after talks with the foreign ministers of Iran and Azerbaijan, did not say what measures Turkey might take, but Vatan newspaper said it could send more troops to the site.
Suleyman Shah was the grandfather of Osman I, founder of the Ottoman dynasty which for centuries ruled Anatolia, much of the Middle East and southeastern Europe and a swathe of north Africa from its capital in Constantinople, modern-day Istanbul.
Turkey has been a strong critic of President Bashar al-Assad since the Syrian conflict began three years ago and has taken in more than 700,000 Syrian refugees.
It has backed moderate rebels seeking to oust Assad, but opposes the militant Islamists who now dominate the insurgency.
The fighting has killed more than 140,000 people, according to the British-based, pro-opposition Syrian Observatory for Human Rights, and is destabilising Syria's neighbours. (Reporting by Gareth Jones; Editing by Alistair Lyon)