Every Iranian regime hostile to US: Obama

US President Barack Obama on Tuesday said the differences between Iran's re-elected hardline President Mahmoud Ahmadinejad and his reformist opponent Mir-Hossein Moussavi were minimal.

In an interview with CNBC, Obama made clear he would remain neutral on the outcome of Friday's elections not only because of the 'tough diplomacy' that lies ahead on the nuclear issue, but also to deny a new regime in Tehran a justification for repression because the US was 'meddling'.

"It's important to understand that although there is amazing ferment taking place in Iran, that the difference between Ahmadinejad and Moussavi in terms of their actual policies may not be as great as has been advertised," Obama told MSNBC in an interview.

"Either way, we were going to be dealing with an Iranian regime that has historically been hostile to the United States, that has caused some problems in the neighbourhood and is pursuing nuclear weapons," he said.

Obama is under pressure by conservatives to condemn alleged voting fraud which Moussavi's supporters charge denied him victory.

Obama's Republican 2008 rival for the White House, Senator John McCain, challenged Obama to "speak out that this is a corrupt, flawed sham of an election" and that the "Iranian people... should not be subjected to four more years of Ahmadinejad."

While that may have been in the style of former president George W Bush, Obama's approach is much more one of caution.

Regardless of "whoever came out on top in the election," it was important for the US "to engage in the tough diplomacy around those permanent security concerns that we have - nuclear weapons, funding of terrorism," Obama said.

"That's not going to go away, and I think it's important for us to make sure that we've reached out," Obama said, referring to the overtures he has made to open a dialogue since taking office in January.

The US president said it was "up to the Iranian people" to make their decision in the election.

"The easiest way for reactionary forces inside Iran to crush reformers is to say it's the US that is encouraging those reformers," Obama said.

Monday, Obama said he was 'deeply troubled' by the post-election violence, which has claimed at least five lives, but would continue to pursue a 'tough direct dialogue'.

"Ultimately, the question that the leadership in Iran has to answer is their own credibility in the eyes of the Iranian people," Obama told CNBC. "When you've got 100,000 people who are out on the streets peacefully protesting, and they're having to be scattered through violence and gunshots, what that tells me is the Iranian people are not convinced of the legitimacy of the election."

He said he was taking a 'wait-and-see' approach as to whether the regime will respond "with a recognition that the universal principles of peaceful expression and democracy are ones that should be affirmed."