Secret Romney Film: How I Would Bomb America

Further secret filming of Mitt Romney has emerged, with the US presidential candidate appearing to declare how he would carry out a terrorist attack on America if he was leader of Iran.

It comes after footage of the Republican secretly being filmed telling donors his job was "not to worry" about the 47% of American voters who back President Obama because they pay no income tax and depend on the state for healthcare, food and housing.

At the same donors meeting, held in Florida in May, Mr Romney said: "If I were Iran, a crazed fanatic, I'd say let's get a little fissile material to Hezbollah, have them carry it to Chicago, and then if anything goes wrong, or America starts acting up, we'll just say, 'Guess what? Unless you stand down, why, we're going to let off a dirty bomb'.

"I mean this is where we have - where America could be held up and blackmailed by Iran, by the mullahs, by crazy people. So we don't have any option but to keep Iran from having a nuclear weapon."

The remarks made pundits raise further questions about his foreign policy credentials.

New films, posted on the internet by left-leaning magazine Mother Jones, also showed Mr Romney seemingly dismiss Middle East peace talks.

He said: "I look at the Palestinians not wanting to see peace anyway, for political purposes, committed to the destruction and elimination of Israel, and these thorny issues, and I say there's just no way.

"You move things along the best way you can. You hope for some degree of stability, but you recognise that this is going to remain an unsolved problem - and we kick the ball down the field and hope that ultimately, somehow, something will happen and resolve it."

Meanwhile, President Obama has used an appearance on a popular US talk show to respond to Mr Romney's remarks that nearly half of Americans are "victims" who depend on the government.

Speaking on the Late Show with David Letterman, Mr Obama said that the occupant of the White House must "work for everyone, not just for some".

He added: "One thing I've learned as president is that you represent the entire country. There are not a lot of people out there who think they are victims or simply entitled."

Mr Romney, who held a hastily convened press conference following the leaked videos, has since insisted that his comments are evidence of a fundamental difference with Mr Obama's Democrats over the economy, adding the US government should not "take from some to give to the others".

Despite Mr Romney's remarks, the presidential race remains neck-and-neck with just seven weeks to go until voters go to the polls on November 6.

According to the latest AP-GfK poll, Mr Obama is supported by 47% of likely voters and Mr Romney by 46%.