Iran has now produced roughly enough uranium to make a single nuclear bomb, according to atomic experts analyzing the latest report from the U.N. nuclear watchdog agency, The New York Times reported Wednesday.

To date, Iran had enriched about 1,400 pounds of low-enriched uranium suitable for nuclear fuel, according to two confidential reports from the International Atomic Energy Agency that were obtained by The Associated Press.

Several experts told The Times the milestone was enough for a bomb, but Iran would have to further purify the uranium fuel and put it into a warhead design — a technical advance that experts in the West are unsure Iran has been able to achieve.

"They clearly have enough material for a bomb," Richard L. Garwin, a top nuclear physicist who helped invent the hydrogen bomb and has advised Washington for decades, told the newspaper. "They know how to do the enrichment. Whether they know how to design a bomb, well, that’s another matter."

The report found the Islamic Republic was installing, or preparing to install, thousands more of the machines that spin uranium gas to enrich it — with the target of 9,000 centrifuges by next year.

The report on Iran — which also went to the U.N. Security Council — cautioned that Tehran's stonewalling meant the IAEA could not "provide credible assurances about the absence of undeclared nuclear material and activities." And it noted that the Islamic Republic continued to expand uranium enrichment, an activity that can make both nuclear fuel or fissile warhead material.

While that conclusion was expected, it was a formal confirmation of Iran's refusal to heed Security Council demands to freeze such activities, despite three sets of sanctions meant to force an enrichment stop.

Iran denies weapons ambitions, and Syria asserts the site hit more than a year ago by Israeli warplanes had no nuclear functions. But the two reports did little to dispel suspicions about either country.

The U.N. nuclear watchdog agency also said Wednesday that a Syrian site bombed by Israel in 2007 had the characteristics of a nuclear reactor.

The documents were being shared with the 35 nations on the IAEA's board.

On Syria, the agency also said that soil samples taken from the bombed site had a "significant number" of chemically processed natural uranium particles. A senior U.N official, who demanded anonymity because the information was restricted, said the findings were unusual for a facility that Syria alleges had no nuclear purpose.

The same official characterized U.N. attempts to elicit answers from Tehran on allegations that it had drafted plans for nuclear weapons programs as at a standstill.

The Syrian report said "it cannot be excluded" that the building destroyed in a remote stretch of the Syrian desert on Sept. 6, 2007, was "intended for non-nuclear use."

Still, "the features of the building ... are similar to what may be found in connection with a reactor site," it said, suggesting facility's size also fits that picture.

The report took note of Syrian assertions that any uranium particles found at the site must have come from Israeli missiles that hit the building, near the town of Al Kibar. And it cited Damascus officials as saying the IAEA samples contained only a "very limited number" of such particles.

But the report spoke of a "significant number of ... particles" found in the samples.

The senior U.N. official said "the onus of this investigation is on Syria" and noted that the traces were not of depleted uranium — the most commonly used variety of the metal in ammunition, meant to harden ordnance for increased penetration.

Satellite imagery made public in the wake of the Israeli attack noted that the Syrians subsequently removed substantial amounts of topsoil and entombed the building in concrete. But the report also suggested similar activities at three other Syrian sites of IAEA interest.

"Analysis of satellite imagery taken of these locations indicates that landscaping activities and the removal of large containers took place shortly after the agency's request for access," it said.

Beyond one visit in June to the Al Kibar site, Syria has refused IAEA requests to return to that location and examine the three other sites, citing the need to protect its military secrets.

In addition, said the report, "Syria has not yet provided the requested documentation" to back up its assertions that the bombed building was a non-nuclear military facility.

Iran denies such plans, saying it wants to enrich for a future large-scale civilian nuclear program. But suspicions have been compounded by its monthslong refusal to answer IAEA questions based on U.S., Israeli and other intelligence.