ISTANBUL, Sept 21 (Reuters) - President Tayyip Erdogan said on Sunday that no ransom was paid for the release of Turkish hostages held by Islamic State in Iraq and that it was a result of diplomatic and political negotiation.

Turkish intelligence agents brought 46 hostages seized by Islamic State militants in northern Iraq back to Turkey on Saturday after more than three months in captivity, in what Erdogan described as a covert rescue operation.

Erdogan also said he has discussed a buffer zone on the Syrian border with U.S. President Barack Obama and NATO allies at the NATO summit earlier this month.

(Reporting by Seda Sezer; Editing by Mark Potter)