Saeed Jalili, secretary of Iran's Supreme National Security Council and the country's chief nuclear negotiator, paid a surprise visit to Ankara on Monday, Sept 17, to meet Turkish Foreign Minister Ahmet Davutoğlu, according to Today's Zaman.

The meeting, which took place at Davutoğlu's official residence, was closed to the press.

Jalili is scheduled to meet European Union foreign policy chief Catherine Ashton on Tuesday in Istanbul for technical talks on Tehran's disputed nuclear program.

Ashton is spearheading nuclear talks with Iran on behalf of the United States, China, Russia, Britain, Germany and France. Without a deal, the stalemate over Iran's nuclear aspirations could boil over into a regional battle that could destabilize oil markets and damage the fragile global economy.

In a series of negotiation rounds this year, neither side has been willing to budge. The six powers want Tehran to scale back its uranium enrichment program, and in particular to stop refining the element to levels close to weapons-grade, because of their suspicions that Tehran wants to acquire a nuclear bomb.