Iran has significantly increased the amount of uranium it is enriching at a level close to weapon-grade and is sanitizing a site where it is suspected of doing bomb-related experiments, according to a classified UN nuclear watchdog report released Thursday and obtained by Breaking Defense.

Iran continues to block inspectors from the International Atomic Energy Agency (IAEA) from doing the work they need to guarantee that Iran does not seek the bomb, This comes at a time when Israel is wrestling with the question of whether to attack Iran in order to neutralize its nuclear program.

The IAEA report seems to fall short of providing Israel justification to attack Iran immediately. The number of centrifuges actually enriching uranium at the Fordow site, which is built under a mountain and probably invulnerable to air attack, has not changed since May, even if Iran has doubled to over 2,000 the number of centrifuges there. These are all, according to the IAEA report, basic P-1 centrifuges and not more advanced models which Iran is working on. The more advanced centrifuges could radically increase the rate of production.

This would give Iran, as it amasses a stockpile, the ability to “break-out” towards a weapon by enriching quickly to weapon-grade. The current stockpile of 20-percent uranium is 91.4 kilograms, probably enough for one bomb if enriched further, as Iran has used much of what it has produced to make fuel assemblies for a research reactor in Tehran. It also has some 6,000 kilograms of uranium enriched to 3.5 percent, probably enough for four bombs if refined more. Iran insists, however, that its nuclear program is a peaceful effort to generate electricity. The country’s Supreme Leader Ali Khamenei said in Tehran Thursday that seeking nuclear weapons is a “big and unforgiveable sin,” alluding to a fatwa, or religious edict, which Iran has issued against such arms.

Still, Iran’s growing nuclear capabilities will increase concern that it is moving closer to be able to make the bomb. This will take the tension in the Islamic Republic’s stand-off with the international community, especially the United States and Israel, up yet another notch.

Uranium for power reactor fuel is usually enriched to only 3.5 percent. Iran is enriching its uranium up to 20 percent to provide fuel assemblies for the Tehran research reactor which produces isotopes for medical diagnosis. This was to replace fuel it had received from Argentina in 1993, which was enough for 10 years of operation of the Tehran reactor. That was stretched out to 20 years. Iran has already produced enough 20 percent enriched uranium for “at least 10 years of operation” of the Tehran reactor, said an official close to the IAEA investigation, according to reports. He wondered why the Iranians were continuing to make more. Iran says it is thinking of building more research reactors and so would need the fuel, but it has not started any such construction and would be years away from finishing putting up any new reactors.

Only 696 centrifuges, in four cascades of 174 each, are enriching at Fordow. They, and centrifuges at another site in Natanz (pictured above), are churning out “just below 15 kilograms a month,” of uranium enriched to just under 20 percent. This is a tripling of the production rate before Fordow came online in January. It is not clear, said the official, if the other centrifuges set up there have the internal wiring installed to be able to start turning. The official refused to speculate whether Iran was moving at the rate it is at Fordow for political or technical reasons.

The IAEA report was much-anticipated, in hopes that the world could see just how quickly Iran was proceeding with its nuclear program. After a lull since March, during which key meetings between Iran and the United States and five other major international powers were held in Istanbul, Baghdad and Moscow to find a solution to the Iranian nuclear crisis, diplomacy seems to have failed and talk of war has increased. Meanwhile, the toughest sanctions by the United States and the European Union against the Islamic Republic, targeting its central bank and its ability to sell oil came into effect in July, with countries like China, Japan and India pledging to cut down on their purchases of Iranian oil. Leaders in Israel claim the sanctions are not tough enough, while officials in Washington want to give them more time to work.

Israel is concerned that Iranian nuclear work at Fordow could give it “immunity” from an attack. However, Israel did not move against Iran when the Islamic Republic began using centrifuges there and then upped the enrichment from 3.5 percent, the level needed for fuel for power reactors, to almost 20 percent. Weapons-grade uranium is enriched to over 90 percent but the jump from 3.5 to 20 percent is over 80 percent of the way to 90 percent since the process takes place along an exponential curve rather than a straight line.

The IAEA report touched on other matters, such as what is happening at Iran’s Parchin military testing center where the Islamic Republic may have done work on how to trigger an atomic explosion. The suspicious site in Parchin is where “information provided to the Agency by Member States indicates that Iran constructed a large explosives containment vessel” for these trigger experiments. “The information also indicates that this vessel was installed at the Parchin site in 2000. The location at the Parchin site of the vessel was only identified in March 2011. The Agency notified Iran of that location in January 2012.”

Since then, satellite imagery has shown jets of water being used at the site and a pink shroud, which could be a plastic sheet, placed over the building where the explosive containment vessel is believed to be. Soil has also been dug up. The knowledgeable official said this could “hamper” the IAEA’s ability to do environmental sampling, which is when inspectors swipe a cloth on surfaces to pick up atomic and other particles. The water could be used to wash particles away. Digging up earth would also remove particles. The swipes the IAEA inspectors would take now would be “maybe 50 centimeters below the original layer” since so much earth had been scraped off, the official said.

In another development, the IAEA seems to have resolved a “discrepancy” in measuring nuclear waste that raised questions if uranium metal, essential for bomb work, was missing. Iran cooperated in the IAEA’s investigation, earning praise from the official , who said it “behaved as a country should” in dealing with this.