Iran is ringing two deeply buried tunnel complexes with a massive security perimeter linked to its main nuclear complex, a report said Wednesday, amid U.S. and Israeli threats of attack.

The United States and Iran are due to hold their second round of nuclear talks on Saturday, as what both sides are looking for in a deal begins to take shape.

BEIJING (Reuters) - China supports Iran holding talks on its nuclear program with the United States and opposes the use of force and "illegal" unilateral sanctions to try to resolve the issue, Chinese Foreign Minister Wang Yi told Iran's foreign minister on Wednesday.