Iran has called the EU's ban on purchases of oil and the freezing of assets of the country's central bank an "illogical and unfair" move.

Tehran has suggested that the country will find new markets for its oil, allowing it to diversify the economy.

The EU imposed an oil embargo against Iran, to pressure Tehran into resuming talks on the country's controversial nuclear programme.

Iran's foreign ministry said that it is "not possible to impose sanction on Iran" because of the world's long-term need for energy.

The EU sanctions target Iran's central bank and Tejarat bank as well as shipping firms and three senior Revolutionary Guards.

Tejarat bank is believed to have moved tens of millions of dollars to help the Atomic Energy Organisation of Iran to buy uranium. It has 2,000 branches in Iran and foreign offices in France and Tajikistan.

"The world economy is not such that a decision can deprive a country of its existence," the country's intelligence chief Heidar Moslehi was quoted Tuesday by the state IRNA news agency as saying. "Ineffective Western sanctions are not a threat to us, but an opportunity that has brought a lot of benefits."

Some 80 percent of Iran's foreign revenue comes from oil exports, and analysts say that any sanctions affecting its ability to export oil would hit its economy hard. With about four million barrels per day, Iran is the second largest producer in OPEC. It exports about two million barrels a day and consumes the rest domestically.

As far as the Strait of Hormuz crisis is concerned, Republican president Mitt Romney said in the latest presidential debate that he would consider the shutdown of the Strait an "act of war".

"It is appropriate and essential for our military, for our navy to maintain open seas," Romney said at a debate between the four remaining Republican candidates in Tampa, Florida. "Of course it's an act of war."

The US carrier called USS Abraham Lincoln moved through the Strait of Hormuz without incident Sunday despite recent threats from Iran.