TEHRAN -- Iran turned away UN inspectors from an underground site meant to shelter its uranium-enrichment program from attack, diplomats said yesterday, while the country's supreme leader said Tehran will not give up its contentious nuclear technology.
Ayatollah Ali Khamenei's comments came on the eve of a self-imposed deadline to respond formally to Western incentives aimed at curbing its atomic program, deflating hopes that Iran will accept a UN Security Council demand that it freeze enrichment by Aug. 31 or face the possibility of sanctions.
Iran's unprecedented refusal to allow access to its underground facility at Natanz could seriously hamper UN attempts to ensure Tehran is not trying to produce nuclear weapons, and might violate the Nuclear Nonproliferation Treaty, diplomats and UN officials said.
Speaking on condition of anonymity because of the sensitivity of the information, the diplomats and officials from the UN nuclear watchdog, the International Atomic Energy Agency, described other signs of Iranian defiance.
They said Iran denied entry visas to two IAEA inspectors in the last few weeks after doing the same earlier this summer for Chris Charlier, the specialist heading the UN agency's team to Tehran. Additionally, they said, other inspectors were given only single-entry visas during their visits to Iran last week, instead of the customary multiple-entry permits.
Iran's reported actions were likely to harden Western resolve to punish the Tehran regime if it refuses to give up uranium enrichment, which can be used to create the fissile core of nuclear warheads.
Diplomats said yesterday that sanctions could include a ban on the sale of missile and nuclear technology to Tehran, international refusal to grant entry visas to people involved in Iran's nuclear program and a freeze of their assets, and a ban on investment in Iran.
IAEA head Mohamed ElBaradei is to report by Sept. 11 to the agency's board on Iran's compliance with the Security Council deadline on freezing enrichment and on other aspects of Tehran's cooperation with UN inspectors.
The US ambassador to the United Nations, John Bolton, said that ``nothing surprises me about how Iran treats its obligations" under the nonproliferation agreement. He said Iran concealed things from inspectors in the past and alleged Tehran also has falsified data.
Although Bolton said he had no specific knowledge of the reported recent blocking of UN inspectors, he said, ``More obstructionism doesn't surprise me at all."
IAEA officials at the agency's headquarters in Vienna refused to comment.
The Islamic republic has promised to formally respond today to an offer of economic and political rewards for it to freeze enrichment and negotiate strengthened monitoring of its nuclear program.
The proposal from six world powers -- the United States, Russia, China, Britain, France, and Germany -- includes promises that the United States and Europe will provide civilian nuclear technology and that Washington will join direct talks with Iran.
But Iran's supreme leader again ruled out an enrichment freeze.
He accused the United States of pressuring Iran despite Tehran's assertions it is not working on nuclear weapons, as Washington and its key allies contend.
Iran says its enrichment work is intended solely to produce fuel for nuclear reactors that will generate electricity.