WASHINGTON/TEHRAN - President Barack Obama said on Saturday the discovery of a secret nuclear plant in Iran showed a disturbing pattern of evasion by Tehran which added urgency to its Oct 1. talks with world powers.
Iranian officials voiced defiance, with one saying he hoped the plant, under construction southwest of Tehran, would soon be ready and blind Iran's enemies and another expressing shock that the world was not grateful it had revealed its existence.
Iran, which insists its nuclear program is aimed at electricity generation rather than weapons production as feared by the West, will meet the United States and five other powers in the Swiss city of Geneva on Thursday.
The U.S. president warned Iran on Friday it would face sanctions that bite if it did not come clean.
This is a serious challenge to the global nonproliferation regime and continues a disturbing pattern of Iranian evasion, he said on Saturday.
That is why international negotiations with Iran scheduled for October 1 now take on added urgency, Obama said in his weekly radio and Internet address on Saturday.
Britain, France and Germany have joined the United States in raising the specter of new sanctions against Iran if it does not take steps to address concerns about its nuclear program.
Russia also signaled a greater willingness to go along with sanctions while China said it favored a dual track approach of pressure and talks.
U.N. Secretary General Ban Ki-moon expressed grave concern in talks with Iranian President Mahmoud Ahmadinejad on Friday and said Tehran had to show its intentions were peaceful.
He emphasized that the burden of proof is on Iran, Ban's press office said in a statement.
Iran acknowledged it had a uranium enrichment facility near Qom for the first time on Monday in a letter to the U.N.'s International Atomic Energy Agency (IAEA).
Ali Akbar Salehi, head of Iran's atomic energy organization, said Iran had assumed the disclosure would be welcomed.
We are completely stunned and we were anticipating that the Western countries would welcome this measure by Iran, he said.
U.S. officials said the disclosure was aimed at pre-empting an announcement by Western governments, which were aware of the site. The IAEA demanded immediate access.
Ahmadinejad said on Friday the facility was around 18 months from starting up, legal and open for inspection by the IAEA and that Western powers would regret accusing Iran of hiding it.
Low-enriched uranium can be used as fuel for power plants while highly enriched uranium can be used to make bombs.
It's not a secret site, Ahmadinejad told a news conference in New York where he was attending the U.N. General Assembly.
Salehi said the plant was about 100 km (60 miles) south of Tehran toward Qom. There was absolutely no necessity for us to make any announcement on the facility since we are a year-plus before its completion, he said on state television.
Mohammad Mohammadi-Golpayegani, who heads the office of Supreme Leader Ayatollah Ali Khamenei was quoted as saying the plant would start running soon.
This new plant, God willing, will soon become operational and will make the enemies blind, the semi-official Fars News Agency quoted him as saying. Iran already has a uranium enrichment plant near the central city of Natanz.
The foreign minister of Israel, which has refused to rule out pre-emptive military action to stop Iran developing an atomic weapon, called for an unequivocal response.
The disagreement (on whether Iran is developing military nuclear capability) has been done away with, right-winger Avigdor Lieberman told Israel Radio.
Saleh did not say when an inspection would take place but that it would be agreed with the IAEA.
We will announce the time of the inspection of the new facility subsequently in an agreement to be made with the agency, he said.
Obama, who sought to engage Iran after taking office in January, said he remains committed to dialogue but has said if Iran does not respond, sanctions must be considered.
My offer of a serious, meaningful dialogue to resolve this issue remains open, Obama said. But Iran must now cooperate fully with the International Atomic Energy Agency and take action to demonstrate its peaceful intentions.
Alaeddin Boroujerdi, who heads the Iranian parliament's national security and foreign policy commission, warned the West against taking measures which he suggested could affect Tehran's existing cooperation with the IAEA.
(Additional reporting by Hashem Kalantari and Fredrik Dahl in Tehran, Ari Rabinovitch in Jerusalem and Louis Charbonneau in the United Nations; editing by Philippa Fletcher)