VIENNA — U.S. Energy Secretary Steven Chu accused Iran of nuclear "denial, deceit and evasion" on Monday, warning that Tehran's decision to move some uranium enrichment facilities to an underground bunker brings it closer to being able to producing the fissile core of a warhead.
But Iran's nuclear chief remained defiant, announcing that the subterranean Fordow facility would likely start operating within six months. Fereidoun Abbasi blamed Washington and its allies for Tehran's decision to redeploy beneath the earth — a move, he said, was meant to protect its nuclear program from U.S. attack.Story: Report: Iran hangs 22 men for drug trafficking
"The reasons we moved the Fordow site underground is that we want to make the Americans and their allies work tougher in order to destroy these facilities," said the nuclear head, who is also an Iranian vice president. He said the only reason operating enrichment facilities elsewhere have not been attacked "is because we have kept them underground."
US accused of 'devious actions'
"The Americans are so afraid of their lives and their installations and facilities because of the al Qaida attacks," he said. "Why should they not give us the right in order to protect our installations? ... If they would not carry out so many devious actions we would establish our facilities above the ground."
Abbasi spoke to reporters after Chu criticized Iran's nuclear secrecy and refusal to heed U.N. Security Council demands to give up enrichment, notably outspoken comments for the head of an agency whose focus is on domestic energy, environmental and nuclear issues.
"Iran has continued to engage in a long-standing pattern of denial, deceit, and evasion, in violation of its nonproliferation obligations," Chu told a 151-nation meeting of the International Atomic Energy Agency. "Time and time again, Iran has refused to satisfy legitimate concerns about the nature of its nuclear program — selectively rejecting IAEA requests for access to, and information about, its nuclear facilities."Story: Deal to free 2 Americans jailed in Iran hits snags
Iran recently announced that it would increase production of uranium enriched to a higher level than normally needed for reactor fuel at the Fordow facility near the holy city of Qom. That has added to international worries because the path to making weapons grade uranium from higher enriched material is faster and easier than from the low-enriched uranium it has been producing for more than five years at its facility in the central city of Natanz.
Chu referred to such concerns, telling delegates that "expanding, and moving underground, its enrichment to this level marks a significant provocation and brings Iran still closer to having the capability to produce weapons grade uranium.
"Pursuing this course raises serious questions over Iran's peaceful intent," he said, voicing concerns echoed by Britain and France at the conference.
The sharp tone of the exchanges on the opening day of the annual IAEA conference reflected the international divide over Iran's nuclear activities nine years after revelations that the Islamic Republic was secretly assembling a uranium enrichment facility at Natanz.
Since then, the U.N. Security Council has imposed four sets of sanctions on Iran for its refusal to stop enrichment. Tehran says it wants only to make fuel for a future reactor network but international intelligence suggesting it has worked — or is still working — on developing a nuclear warhead and other components of an arms program has sharpened fears that it will use enrichment for making fissile warhead material.
Himself slightly wounded in a 2010 car bomb blast, Abbasi accused Iran's foes of planning to assassinate more Iranian scientists, hinting the IAEA -- the U.N. nuclear watchdog -- was partly to blame.
Abbasi has been personally subjected to U.N. sanctions because of what Western officials said was his involvement in suspected nuclear weapons research.
"Some countries and their intelligence terrorist organizations have focused on assassinating our experts," he said, according to an English translation of his speech.
In July, university lecturer Darioush Rezaie was shot dead by gunmen in eastern Tehran, the third murder of a scientist since 2009. One was killed in a car bomb, the second by a device detonated remotely.
Iran has said the attacks were the work of enemies that wished to deny it the right to develop nuclear technology which it says is aimed at generating electricity.
The Associated Press and Reuters contributed to this report.