WASHINGTON - UN inspectors and intelligence specialists in western countries believe Iran may be preparing to build at least two additional secret nuclear sites, The New York Times reported Sunday.

The newspaper said the suspicions were prompted by recent comments by a top Iranian official, who in an interview with the Iranian Student News Agency, said President Mahmoud Ahmadinejad had ordered work to begin soon on two new plants.

The plants, said Ali Akbar Salehi, head of Iran’s Atomic Energy Organization, "will be built inside mountains," presumably to protect them from attacks, according to The Times report.

"God willing, we may start the construction of two new enrichment sites" in the Iranian new year, which began March 21, Salehi was quoted as saying.

The report follows an announcement by Tehran last month that it was considering building two more uranium enrichment plants inside mountains to protect them from air strikes.

Iran followed that with a letter to the International Atomic Energy Agency saying it was prepared to buy fuel for a nuclear reactor or swap its own stockpile of low-enriched uranium for the fuel, but on its own territory.

Senior White House aide Valerie Jarrett said that the US administration is continuing to ramp up international support against Tehran's atomic aims.

"What I can tell you is what the president has said consistently, which is that we're going to continue to put pressure on Iran," Jarrett told ABC television's "This Week" program.

"The fact that the president and Russia are about to sign the START Treaty is a good sign that we're making cooperation and good progress with countries such as Russia," she said.

"We're going to have a coalition that will really put pressure on Iran and try to stop them from doing what they're trying to do."

She added: "We're seeing steady progress in terms of a world coalition that will put that pressure on Iran."

Last September, US President Barack Obama revealed the evidence of a hidden Iranian nuclear site at Qum.

US officials say they share the International Atomic Energy Agency's suspicions and are examining satellite evidence about a number of suspected sites in Iran, The Times said.

But they have found no solid indications yet that Iran plans to use the new sites to produce nuclear fuel, the report said. Also, US officials are not certain about the number of sites Iran may be planning.

But even if the sites are built, US officials believe they would pose no immediate threat or change US estimates that it will still take Iran one to four years to obtain the capability to build a nuclear weapon, the paper said.

They think it would probably take several years for Iran to enrich uranium at any of the new sites, The Times noted.

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