The United Nations Security Council last week slapped a third set of sanctions against Tehran over its refusal to halt uranium enrichment, which the United States and Europe say is for nuclear armament.

The Islamic Republic has denied Western accusations that is working on an atom bomb, saying it is for peaceful purposes and an inalienable right.

"The sanctions have nothing to do with our oil and gas industry," Abbas Araghchi, Iran's new ambassador to Tokyo, told reporters.

"I can confirm that we have been an oil supplier for Japan and will remain a reliable supplier for Japan in the future," he said.

Iran is the world's fourth largest oil producer but its ambitious development plans are held back by a lack of investment in the face of US pressure on firms not to deal with Tehran.

Japan, which has virtually no natural energy resources and is a strong proponent of nuclear energy, imports nearly all of its oil from the Middle East.

In a rare break with the United States, Japan has maintained friendly relations with Iran even after the 1979 Islamic Revolution.

But Japan, the only nation to have suffered an atomic attack, has gradually become more critical of Iran's nuclear drive. In 2006, Japan pulled out of a project to develop Iran's largest onshore oilfield at Azadegan.

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