ANKARA (Reuters) -- Turkey said on Sunday Syria had shot down its military aircraft in international waters on Friday without warning and declared it would formally consult with NATO allies on a reaction.

Turkish Foreign Minister Ahmet Davutoglu, speaking some 48 hours after the plane was shot down near the sea borders of both countries, told state broadcaster TRT the plane had been clearly marked as Turkish and dismissed Syria's earlier statement it had not known the plane belonged to Turkey.

The shooting down of the aircraft has added a further serious international dimension to the more than year-long uprising against President Bashar Assad, that Turkey, along with other Western and Arab countries, has supported on the world diplomatic stage.

Turkey is giving shelter to the rebel Free Syria Army, and accommodating refugees on its southeastern border with Syria, some 50 km from where the Turkish aircraft was shot down. But it denies providing arms for the insurgents.

Davutoglu said he would present the incident formally to the NATO military alliance this week under article four of its founding treaty.

The article provides for states to "consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the parties is threatened."

It stops short of the explicit mention of possible armed responses cited in article five.

Iranian Foreign Minister Ali Akbar Salehi urged Turkey and Syria late on Saturday to show restraint over the incident, his ministry said.

In a telephone conversation with Davutoglu, Salehi said he hoped the two sides would "settle the issue peacefully to maintain regional stability", read a statement on the Iranian Foreign Ministry's website.

Iran has supported Assad since anti-government protests erupted across the country early last year and grew into an armed uprising.