Iran's president has confirmed for the first time that a computer worm affected centrifuges in the country's uranium enrichment program.
Iran has previously denied the Stuxnet worm, which experts say is calibrated to destroy centrifuges, had caused any damage, saying they uncovered it before it could have any effect.
But President Mahmoud Ahmadinejad has said it "managed to create problems for a limited number of our centrifuges." Speaking to a press conference Monday, he said the problems were resolved.
Earlier in November, U.N. inspectors found Iran's enrichment program temporarily shut down, according to a recent report by the U.N. nuclear watchdog. The extent and cause of the shutdown were not known, but speculation fell on Stuxnet.
THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
TEHRAN, Iran (AP) -- Assailants on motorcycles attached magnetized bombs to the cars of two nuclear scientists in Tehran on Monday, killing one and wounding another who is on a U.N. sanctions list for suspect activity. The president accused Israel and the West of being behind the attacks.
The wounded scientist, Fereidoun Abbasi, is specified by a 2007 U.N. resolution for sanctions because of suspected links to secret nuclear activities, describing him as a Defense Ministry scientist. Iranian media said he was a member of Iran's Revolutionary Guard, the country's strongest military force.
The other scientist, who died in the attack and does not appear in any U.N. resolutions, was involved in a major project with Iran's nuclear agency, said the agency's chief, Ali Akbar Salehi, though he did not give specifics.
Iranian officials said they suspected the assassination was part of a covert campaign aimed at damaging the country's nuclear program, which the United States and its allies say is intended to build a weapon -- a claim Tehran denies. At least two other Iranian nuclear scientists have been killed in recent years, one of them in an attack similar to Monday's.
"Undoubtedly, the hand of the Zionist regime and Western governments is involved in the assassination," President Mahmoud Ahmadinejad told a press conference. He said the attack would not hamper the nuclear program.
Asked about the Iranian accusations, Israeli government spokesman Mark Regev said Israel did not comment on such matters. Washington has strongly denied any link to previous attacks.
The two separate attacks, as described by Iranian officials, appeared sophisticated.
In each case, assailants on motorcycles approached the cars as they were moving through Tehran and attached magnetized bombs to the vehicles, Tehran police chief Hossein Sajednia said. The bombs exploded seconds later, he said, according to the state news agency IRNA.
He said no one has been arrested in connection with the attack nor no one has so far claimed responsibility.
The bombings both took place in the morning, but there were conflicting reports on what time each took place. The bombs went off in two separate locations, in north and northeast Tehran, that lie about a 15-minute drive apart without traffic.
The slain scientist, Majid Shahriari, was a member of the nuclear engineering faculty at Shahid Beheshti University in Tehran. His wife, who was in the car with him, was wounded.
Shahriari cooperated with the Atomic Energy Organization of Iran, said Salehi, a vice president who heads the organization. "He was involved in one of the big AEOI projects, which is a source of pride for the Iranian nation," Salehi said, according to IRNA, without giving any details on the project. Salehi also said the killed scientist was one of his own students.
"They (Iran's enemies) are mistaken if think they can shake us," Salehi said, weeping, as he spoke later on state TV.
The AEOI is in charge of Iran's nuclear activities, including its uranium enrichment program, which the United Nations has demanded be halted.
The other attack targeted Abbasi, who was wounded along with his wife.
Abbasi is on a sanctions list under U.N. Security Council resolution 1747, passed in 2007, which described him as a Defense Ministry scientist with links to the Institute of Applied Physics,working closely with Mohsen Fakhrizadeh, a scientist believed to be heading secret nuclear projects.
A pro-government website, mashreghnews.ir, said Abbasi holds a Ph.D. in nuclear physics and is a Revolutionary Guard member. It said he was also a lecturer at Imam Hossein University, affiliated to the Guard. The United States accuses the Guard of having a role in Iran's nuclear program.
The site said Abbasi was a laser expert at Iran's Defense Ministry and one of few top Iranian specialists in nuclear isotope separation.
Isotope separation -- meaning the isolating of a specific isotope of an element -- is a process needed for a range of purposes, from producing enriched uranium fuel for a reactor, to manufacturing medical isotopes to producing a bomb.
Iran says its nuclear program is intended entirely for peaceful purposes, including producing electricity. The U.N. has demanded a halt to uranium enrichment because it can be used to produce reactor fuel or a bomb, but Tehran insists it has a right to pursue the technology.
Iran has continued to portray its nuclear program as being under constant pressure from the West and its allies. These include alleged abductions of nuclear officials and, more recently, a computer worm known as Stuxnet that experts say was calibrated to destroy uranium-enrichment centrifuges by sending them spinning out of control. Iran says its experts stopped Stuxnet from affecting systems at its nuclear facilities.
Monday's attacks bore close similarities to another in January that killed Tehran University professor Masoud Ali Mohammadi, a senior physics professor. He was killed when a bomb-rigged motorcycle exploded near his car as he was about to leave for work.
There are several active armed groups that oppose Iran's ruling clerics, but it's unclear whether they could have carried out the apparently coordinated bombings in the capital. Most anti-government violence in recent years has been isolated to Iran's provinces such the border with Pakistan where Sunni rebels are active and the western mountains near Iraq where Kurdish separatists operate.
In 2007, state TV reported that nuclear scientist, Ardeshir Hosseinpour, died from gas poisoning. A one-week delay in the reporting of his death prompted speculation about the cause, including that Israel's Mossad spy agency was to blame.
The latest attacks come a day after the release of internal State Department memos by the whistle-blower website WikiLeaks, including several that vividly detail Arab fears over Iran's nuclear program and its growing political ambitions in the region. In some memos, U.S. diplomats say Arab leaders advocated a U.S.-led attack on Iranian nuclear facilities.
Ahmadinejad dismissed the leaks as "mischief" aimed at damaging Tehran's ties with the Arab world.