Obama 'outraged' by Iran's violent crackdown

US President Barack Obama on Tuesday strongly rejected Iranian accusations of interfering in the election crisis and in some of his toughest language yet said he was 'appalled and outraged' by the violent crackdown on protestors.

Obama dismissed as 'patently false and absurd' Iranian suggestions that his administration was behind the protests, accusing Iranian officials of trying to avoid questions about the legitimacy of the election by blaming the US.

"The Iranian people are trying to have a debate about their future. Some in the Iranian government are trying to avoid that debate by accusing the United States and others outside of Iran of instigating protests over the elections," Obama said. "These accusations are patently false and absurd."

"This tired strategy of using old tensions to scapegoat other countries won't work anymore in Iran," he added.

Obama has been under increasing pressure from conservative Republicans who accuse him of responding too timidly to the turmoil in the Islamic state - charges Obama rejected during the White House press conference.

Tens of thousands of Iranians have taken to the streets since the June 12 election accusing the government of rigging the results to ensure the victory of hardliner incumbent President Mahmoud Ahmadinejad over reformist Mir-Hossein Moussavi.

Seeking to rebuff criticism, Obama sharpened his tone, warning the Iranian government that its handling of the dispute will affect its relations with the rest of a closely watching world.

"No iron fist is strong enough to shut off the world from bearing witness to peaceful protests of justice," said Obama, who has previously pledged to pursue direct dialogue with Tehran to address 30 years of hostile relations and contentious issues like Iran's nuclear programme and alleged support for terrorism.

The US will await the outcome of the crisis before determining how to proceed in trying to engage Iran and bring it into the community of nations, Obama said.

"What we've been seeing over the last several days, the last couple of weeks, obviously is not encouraging in terms of the path that this regime may choose to take," he said. But he did not rule out the possibility of opening discussions.

"My position coming into this office has been that the United States has core national security interests in making sure that Iran doesn't possess a nuclear weapon and it stops exporting terrorism outside of its borders," he said.

"We have provided a path whereby Iran can reach out to the international community, engage, and become a part of international norms," Obama said. "It is up to them to make a decision as to whether they choose that path."

Obama condemned the violent repression against dissent that has killed at least one dozen people and hurt scores more.

"The United States and the international community have been appalled and outraged by the threats, the beatings and imprisonments of the last few days," he said. "I strongly condemn these unjust actions."

"We've seen the timeless dignity of tens of thousands of Iranians marching in silence," Obama said. "We've seen people of all ages risk everything to insist that their votes are counted and that their voices are heard."

Obama also for the first time commented on Neda Agha Soltan, the Iranian woman whose shooting death was captured on film and subsequently made its way around the world over the internet.

"It's heartbreaking," he said. "And I think that anybody who sees it knows that there's something fundamentally unjust about that."