Iran's continued defiance on the nuclear issue will lead to more isolation and economic pressure on Teheran, Reuters quoted US Secretary of State Hillary Clinton as saying on Friday.
"There will be accompanying costs for Iran's continued defiance: More isolation and economic pressure, less possibility of progress for the people of Iran," Clinton said in a speech at the Brookings Institution.
"We have made clear our desire to resolve issues with Iran diplomatically. Iran must now decide whether to join us in this effort," she added.
On Thursday, Iranian President Mahmoud Ahmadinejad said his country has no need for nuclear weapons, but refrained from explicitly ruling out that Teheran would acquire such arms.
"Nuclear arms, we believe they belong to the past and the past generation," Ahmadinejad was quoted by AFP as saying in an interview with NBC television. "We do not see any need for such weapons," he said.
The Iranian leader went on to stress that the Islamic republic has "always believed in talking, in negotiation."
However, when asked if he could issue a clearer statement ruling out Iran's obtaining nuclear weapons, Ahmadinejad replied: "You can take from that whatever you want Madam."
Earlier Thursday, AP published a secret IAEA report claiming Iran is on the way to developing a missile system able to carry an atomic warhead, and also had the know-how to build a bomb.
According to the IAEA document seen by The Associated Press, Iran has "sufficient information" to build a bomb and is likely to "overcome problems" on developing a delivery system.
However, the IAEA denied the AP report. "With respect to a recent media report, the IAEA reiterates that it has no concrete proof that there is or has been a nuclear weapons program in Iran," the statement said.
Meanwhile, Iran's ambassador to the International Atomic Energy Agency Ali Asghar Soltanieh said Teheran's upcoming nuclear talks with the West pose a "real, new window of opportunity," and suggested that Teheran is prepared to address concerns about its nuclear intentions.
In an interview with the Washington Post published on Thursday, Soltanieh warned against attempts to intimidate his country with threats of new sanctions and reiterated that Iran has a basic right to pursue peaceful nuclear power.
"This is the best course of action, and this is a real, new window of opportunity that is being opened by the Iranian nation," Soltanieh reportedly said of the nuclear talks Iran is set to hold with the five permanent members of the UN Security Council - the UK, China, France, Russia and the US - as well as Germany.
The West, he said, "should immediately and promptly seize this opportunity."
Meanwhile, Uzi Rubin, founder of the Arrow missile and former head of the Israeli Homa missile defense agency, said Friday morning that Ahmadinejad's insistence that the Islamic republic was not pursuing nuclear weapons was contrary to US and Israeli assessments.
Speaking to Army Radio, Rubin also stressed that Washington's decision to shelve its plan for an Eastern European missile defense shield did not indicate that that the White House no longer believed Iran was a danger.
"The US president described Iran as a threat," said Rubin, adding that Washington had changed its missile defense policy "not because Iran is no longer a threat, but because their missiles cannot reach the US."
"Not only that, added the Arrow founder, "but he [US President Barack Obama] said they [the Iranians] had developed an even greater capability for missiles that can reach Europe."