"The discussions were about arms cooperation and S-400 systems in particular," Rosoboronexport spokesman Vyacheslav Davydenko told AFP, confirming a report about the talks.

The S-400 is Russia’s most advanced air defense system and has previously not been exported, according to Rosoboronexport.

It has a longer range than U.S.-built Patriot missiles and a previous Russian system, the S-300.

Moscow has a contract to supply S-300s to Iran, but the deal is on hold, reflecting tension around the Islamic Republic and objections from Israel and the United States. 

The RIA-Novosti news agency reported earlier that Turkish and Russian defense officials discussed the possible sale of S-400s at the International Defense Industry Fair in Istanbul.

Sources in the Russian delegation said the sale would depend on the resolution of a dispute between Moscow and the West over a planned U.S. missile shield in Eastern Europe, RIA-Novosti reported.

The S-400 has a range of 400 kilometers (250 miles) and is capable of taking out radar-resistant Stealth aircraft and other advanced targets, according to the Web site of its manufacturer, Almaz-Antey.

Turkey, a traditional rival of Russia, has long bought many of its weapons from the United States.

Photo is an archive image.