Pentagon chief Leon Panetta on Friday warned there was no guarantee a US military strike on Iran would hit intended targets linked to Tehran's nuclear program, saying the sites are "difficult to get at."

The US defense secretary has recently voiced his misgivings about bombing Iran in a series of public remarks, amid speculation Israel may take pre-emptive action to prevent Tehran from acquiring atomic weapons.

But for the first time Friday, Panetta -- the former director of the CIA -- appeared to suggest Iran's underground nuclear facilities might survive air strikes.

"The indication is that at best it (military action) might postpone it (Iran's nuclear program) maybe by one or possibly two years," he said in remarks at an event organized by the Brookings think-tank in Washington.

"It depends on the ability to truly get at the targets that they're after. Frankly, some of those targets are very difficult to get at," Panetta said.

Defense analysts have often pointed out that Iran has sought to hide sensitive nuclear sites and material in underground facilities, and Western officials privately acknowledge the hidden targets pose a military challenge.

Panetta reiterated his view that a strike against Iran could benefit the regime in Tehran at a moment when it is "off-balance" and out of step with popular uprisings sweeping the region.

He also said a strike could derail the European and US economies, endanger US troops and trigger an unpredictable cycle of violence.

"Lastly, the consequence could be that we would have an escalation that would take place that would not only involve losing lives but I think could consume the Middle East in confrontation and conflict that we would regret.

"So we have to be careful about the unintended consequences of that kind of attack," Panetta said.

Iraq blast was assassination attempt says official
Baghdad (AFP) Dec 2, 2011 - Iraqi Major General Qassim Atta on Friday said an explosion near parliament was a botched attempt to kill the prime minister, after an official termed it an attempt on the parliament speaker's life.

At least one person was killed and two wounded in the blast near the Iraqi parliament building on Monday, the cause of which was disputed. MP Muayid al-Tayyeb was one of those hurt.

"The intelligence information that we obtained showed that this operation was conducted to target the prime minister," Baghdad security spokesman Atta told AFP.

"The person was supposed to bring the car inside the parliament parking, and leave it there for four days until (Prime Minister Nuri) al-Maliki attended a session of the parliament," Atta said.

"He failed to bring the car inside the parking, so he blew himself up," he said, adding that "the car entered the Green Zone with a convoy."

"We arrested two groups involved in this operation," Atta said.

He told a news conference on Friday that the vehicle was a black SUV containing 20 kilogrammes of locally-made explosives.

A burned body has been found at the scene was suspected of being the body of the "terrorist," he said.

Iraqi security officials, an MP and a US military spokesman had on Monday given a laundry list of potential causes for the blast, saying that it was alternatively from a mortar shell, a suicide bomber, or a magnetic "sticky bomb."

Atta is the second official to allege that the blast was an attempt on a high-ranking Iraqi politician's life.

Aidan Helmi, media adviser to parliament speaker Osama al-Nujaifi, said on Monday that the explosion was caused by a suicide bomber and called it a botched "assassination attempt" on Nujaifi.

"One man in a black vehicle that looks like the vehicles of Nujaifi's convoy tried to enter the VIP gate of parliament," possibly aiming to join the speaker's convoy, Helmi told AFP.

"When he tried to enter, the guards asked him for a special badge, so he backed up, hitting a car behind him and the pavement.

"He then got out of the car and started arguing with the driver of the car behind him, and suddenly he blew himself up."

"Mr Nujaifi was in his room, and he was late because I talked to him for 15 minutes," Helmi said.

"This is an assassination attempt against Mr Nujaifi. The question is not which party the attacker belonged to, but rather how he managed to arrive here with this vest."