Western diplomats and private-sector analysts strongly doubt Iran President Mahmoud Ahmadinejad's claim today that his country is producing nuclear fuel on an industrial scale, and believe his announcement saying as much was designed purely for domestic political reasons, sources tell FOX News.

Ahmadinejad was joined in the claim in a separate announcement by the country's top nuclear negotiator, Ali Larijani, who said that Iran was feeding uranium gas into 3,000 centrifuges. U.S. experts say 3,000 centrifuges are in theory enough to produce a nuclear weapon, and possibly successfully within a year.

Foreign and domestic sources tell Fox News that Iran has installed at most 1,320 centrifuges, probably fewer, and the country has not yet even mastered the enrichment process with its first "cascade" of centrifuges — its first set of 164 centrifuges.

In the enrichment process, uranium gas is pumped into centrifuges, which spin and purify the gas. Enriched to a low degree, the result is fuel for a reactor that can be used in electric power generation, but enriched to a high degree it creates the material for a nuclear warhead.

One source repeated a widely reported fact that Iran has installed two above-ground pilot cascades of 328 centrifuges. The source added that Iran has built another six or seven cascades below ground, which could be an additional 1,148 centrifuges.

But the hardest part of mastering the nuclear fuel process — for peaceful purposes or otherwise — is getting first cascade to work properly, and for months at a time. With a functioning cascade, it is easier to replicate the process.

But sources tell Fox News Iran's pilot cascade operates "haphazardly," and mostly "dry" or "on vacuum" — without the introduction of the uranium gas.

Sources say that by building multiple cascades without necessarily building one that has succeeded in the enrichment process is how the country can make announcements like today's that might have a strong domestic political effect but do not mean the program is moving along as fast as it might seem.

Judging the strength of Iran's nuclear program is difficult though, the sources said, because outside analysis is based entirely on what is known by the U.N.'s International Atomic Energy Agency and aerial reconnaissance.

Ahmadinejad previously has claimed that his country's scientists are conducting research into the use of advanced, more time-efficient P-2 centrifuges. That could mean a highly accelerated timetable for mastery of the fuel cycle. Iran is believed to have acquired some P-2 design technology from A.Q. Khan, the renegade Pakistani nuclear scientist who supplied similar materiel to North Korea and Libya.

Some analysts assert that Iran is proceeding at the rate of installing one cascade a week, and should reach its immediate goal of 3,000 — despite today's claims already to have done so — by the end of May.

Other sources could not confirm the one-cascade-per-week claim. However the general consensus is that if Iran develops the ability to operate 3,000 centrifuges successfully for one year, the country will have enough enriched uranium to produce a nuclear weapon.

Despite the skepticism over the country's claims, a real threat remains, analysts believe: Iran already has the missiles that can deliver a nuclear warhead.

FOX News James Rosen and The Associated Press contributed to this report.