TEHRAN (Reuters)- Iran’s supreme leader said on Thursday restoring ties with the United States now would harm the Islamic state, but he did not rule it out in the future.

“Not having relations with America is one of our main policies but we have never said this relationship should be cut forever,” Ayatollah Ali Khamenei said in a speech in the central province of Yazd, state television reported.

“Certainly, the day when having relations with America is useful for the nation I will be the first one to approve this relationship.”

Khamenei, Iran’s highest authority, also made clear Tehran would not suspend atomic work the West suspects Iran wants to master so it can build nuclear bombs. Iran says its program is aimed at generating electricity.

“The Iranian nation in 20 years needs to have at least 20,000 megawatt of nuclear electricity,” he said, referring to plans to build a network of nuclear power plants in the world’s fourth-largest oil producer.

The United States cut ties with Tehran shortly after Iran’s 1979 Islamic Revolution. The two countries are at odds over Tehran’s atomic ambitions and also disagree over who is to blame for the violence in Iraq.

Khamenei, who like other Iranian leaders often rails against the West, suggested the example of Iraq showed the United States would remain a “danger” even if the two countries had relations.

“Establishing this relationship now would be harmful for us and naturally we shouldn’t follow it,” he said.

Iranian and U.S. officials eased a diplomatic freeze lasting almost three decades by holding three rounds of talks in Baghdad since May, but discussion was limited to Iraq.

U.S. Secretary of State Condoleezza Rice said last month Washington was open to better relations with Iran if it halted its nuclear work, something Tehran has repeatedly refused to do.

Khamenei rejected the suggestion by Washington and Moscow that Iran should stop nuclear uranium enrichment after Russia began delivering fuel in December to Iran’s first nuclear power plant in Bushehr.

“This is like telling a country with huge oil reserves that it should provide for its oil needs from abroad,” he said.

Enriched uranium can be used as fuel for power plants but also, if refined much further, provide material for bombs.

Khamenei said Iran’s temporary suspension of nuclear enrichment in 2003, under former President Mohammad Khatami, had shown the West’s promises were “empty” and he suggested he had intervened to resume the program.

The United States is pushing for a third round of U.N. sanctions against Iran for not halting enrichment, even though a U.S. national intelligence estimate last month said Iran had stopped its nuclear weapons program in 2003.

Iranian officials say the country needs domestic nuclear fuel production for other power plants it wants to build so that it can export more of its oil and gas.