Top EU and Iranian representatives are holding talks on restarting stalled negotiations over Tehran's nuclear program.

Foreign policy Chief Catherine Ashton and Iran's chief nuclear negotiator Saeed Jalili are meeting in Istanbul on Tuesday.

The meeting follows a round of talks in July where an attempt was made to restart nuclear negotiations between Tehran and six world powers that fizzled in June. The U.S. and other countries fear the failure of negotiations could prompt Israel to make good on its threat to attack Tehran's nuclear installations.

Israeli Prime Minister Benjamin Netanyahu made a direct appeal to American voters on Sunday to elect a president willing to draw a "red line" with Iran.

The EU says the talks are a chance to stress the need for a "meaningful confidence-building step and ... more flexibility" from Iran.