Iran has told U.N. nuclear officials that it plans to add potentially hundreds of next-generation centrifuge machines to its main uranium-enrichment plant, a move that could dramatically boost its ability to produce the fuel used in nuclear power plants and — potentially — in nuclear bombs.

The notification came in a letter last week in which Iran said it would begin installing the more powerful centrifuges at its Natanz plant, south of Tehran, which already has been enriching uranium for nearly a decade, according to a Western diplomat briefed on the plans.

The new machine, the IR2M, is believed to be vastly superior to the clunky, 1970s-era IR1 machine that Iran currently uses, giving Iran the ability to produce up to four times as much enriched uranium per machine. Iran claims the enriched uranium would be used exclusively for nuclear power plants, but U.S. officials suspect that Iran is using nuclear energy to keep open its options to pursue a weapons program.

Iran’s Jan. 23 letter to the International Atomic Energy Agency did not identify how many centrifuges it planned to install, or when the changes would occur. But U.N. officials inferred from the letter that hundreds of machines, if not more, would be added to one wing of the Natanz plant, according to the official, who insisted on anonymity in discussing confidential correspondence. The U.N. watchdog agency informed member states about Iran’s plans in an internal memo and said it was pressing Iranian officials for details, the diplomat said.

Iran has been operating a small number of IR2M machines for several years in a pilot plant on the grounds of the Natanz complex. Recent reports by IAEA inspectors indicated that the new machines seemed to be functioning well, as Iranian engineers appeared to work out technical glitches that had thwarted previous plans to install large numbers of the advanced machines.

While still awaiting hard evidence that the new machines can function on an industrial scale, Western intelligence officials and weapons experts said they were not surprised by Iran’s announcement. Analysts have predicted that Iran would eventually master the technology for more advanced centrifuges, potentially putting its nuclear program on a much faster track.

“It was clear that they were making progress with advanced centrifuges,” said a second Western diplomat whose government closely follows Iran’s nuclear program. “It was always a matter of time before the IR2s were working in large numbers, allowing them to enrich uranium — even weapons-grade-uranium — much faster.”

A key remaining question is whether Iran can acquire sufficient quantities of the high-strength materials used to make components of the IR2M. Because of sanctions, Iran is believed to have a limited stock of metals such as maraging steel and carbon fiber, potentially limiting the number of advanced machines it can build, weapons experts say.

Other analysts suggested that Iran’s letter may be a bargaining ploy as Iranian officials prepare for nuclear talks with the United States and other world powers. Greg Thielmann, a former official with the State Department’s intelligence branch, noted that Iran has adopted a more cautious stance in recent months, deliberately slowing the growth rate of its uranium stockpile in an apparent effort to lower tensions with Israel and the West. Strikingly, he said, Iran’s letter made no mention of plans to install the new machines in Iran’s underground Fordow enrichment plant, a facility built in secret inside a mountain bunker shielded from possible airstrikes.

“I wonder if they wanted to get more negotiating leverage, demonstrate their technological prowess, but did not want to fulfill the most alarming predictions of those who argue that Iran is intent on breaking out” or making a dash for the bomb, said Thielmann, now a senior fellow with the Arms Control Association.