"We are aware of this new site that has been referred to. We do not have any indication that this site has nuclear-related activities. However, we continue to investigate this and other sites (in Iran)," International Atomic Energy Agency (IAEA) chief Muhammad al-Baradai told reporters in Vienna on Friday.
In Tehran, Iran threatened to take the IAEA to the International Court of Justice if it sets a deadline for the Islamic Republic to commit to a new freeze on uranium enrichment activities.
Influential former president Akbar Hashemi Rafsanjani told worshippers at Friday prayers at Tehran University that Iran would lodge a complaint at the Hague tribunal against the IAEA for acting outside its powers.
"If it sets a deadline to halt some of our nuclear activities we have the right to go to the Hague court," Rafsanjani said.
Rafsanjani cries foul
"Passing such an unjust resolution with a deadline is a violation of the law."
Washington accuses Iran of pursuing nuclear arms under cover of a civilian atomic programme. Iran denies this, saying it only wants to generate electricity.
A diplomat said on Thursday that Washington had reached a compromise with France, Britain and Germany on a resolution calling for an immediate halt to the enrichment programme, but not setting a deadline.
The text still has to be approved by most of the 35 nations on the IAEA governing board.
Meanwhile, the IAEA on Friday put off discussing Iran's nuclear programme as member states were still debating the draft resolution, an IAEA spokesman said in Vienna.
"Passing such an unjust resolution with a deadline is a violation of the law"
Akbar Hashemi Rafsanjani,
former president, Iran
The Mexican chairwoman of the 35-nation board of governors, Patricia Espinosa Cantellano, said "negotiations are still ongoing" on the resolution.
"We hope in the next few days to deal with this item," Espinosa Cantellano said.
Iranian delegation chief Hossein Mousavian said Iran would decide on the draft resolution within two or three days. He added the Islamic Republic would weigh in on its "national interests" whether to respect the IAEA call or resume enrichment.