WASHINGTON — International nuclear inspectors will soon report that Iran has installed hundreds of new centrifuges in recent months and may be speeding up production of nuclear fuel while negotiations with the United States and its allies have ground to a near halt, according to diplomats and specialists briefed on the findings.

Almost all of the new equipment is being installed in a deep underground site on a military base near Qom that is considered virtually invulnerable to military attack. It would suggest that a boast by senior Iranian leaders late last month — that the country had added upward of 1,000 new machines to its installation despite Western sabotage — may be true.

The report will also indicate, according to the officials familiar with its contents, that Iran is increasingly focused on enriching uranium to a level of 20 percent — a purity it says it needs for a specialty nuclear reactor used for medical purposes, but that outside specialists say gets it most of the way to the level needed to produce a workable nuclear bomb. The report does not attempt to address the question of whether Iran has made a decision to build a nuclear weapon; US intelligence officials believe it has not.

It is unlikely that Iran has begun to use the new centrifuges to produce fuel, and even with a significant increase in fuel production it would still take months, at the least, to produce a crude weapon. By most US government estimates, Iran would need at least two years to develop a workable warhead that could fit atop a missile.

Nonetheless, the report by the International Atomic Energy Agency’s analysts, first reported by Reuters, is likely to renew the debate over Iran’s intentions at a time when Israeli officials are stepping up their warnings that the window to conduct a preemptive military strike is closing.

A faction led by Israel’s defense minister, Ehud Barak, will almost certainly argue that Iran has moved closer to a point at which so much equipment is installed in the underground facility, called Fordow, that it will soon be too late to stop Iran from producing a weapon, should it choose to do so.

The report could also become an issue in the presidential race. The presumptive Republican nominee, Mitt Romney, used a trip to Israel last month to declare that President Obama had wasted time with fruitless negotiations with Iran and that Iran had taken advantage of the time to advance its nuclear program.

‘‘This will stir more discussion of how much time is left for diplomacy,’’ Olli Heinonen, the former chief inspector for the International Atomic Energy Agency, and now a fellow at Harvard’s Belfer Center for Science and International Affairs, said Thursday. ‘‘Even if the new centrifuges are not operating yet, a thousand new ones would represent a 20 percent increase — and an increased production level will be a red line for many people.’’

It may also make it harder to win a diplomatic deal. Under an offer that the United States and its Western allies, along with Russia, presented to Iran privately in the late spring, Tehran would be allowed to retain some enrichment capability if it turns over its entire stockpile of 20 percent-enriched uranium and answers the questions posed by international inspectors about evidence that it has worked on a weapon. While Iranian officials have privately expressed some interest in the plan, the deal has gone nowhere, and no new negotiating sessions are scheduled, US officials say.

“For now, the talks are dead in the water,’’ one senior official said Thursday.

Obama and his staff have been trying to avoid a crisis over Iran that would unfold in the last months of the presidential election. But the report, expected to be the last by the atomic energy agency before Election Day, will lay out a stark reality: Despite increasingly painful sanctions, and a covert program called ‘‘Olympic Games’’ that aimed to slow the Iranian program with cyberattacks, Iran has made substantial progress in producing enriched uranium in recent years — from about one bomb’s worth when Obama took office in 2009 to the equivalent of about five bombs’ worth today.

But the fuel would require considerable additional enrichment before it was usable in a weapon, and even then, Obama and others have insisted, the United States would almost certainly know, and have time to act, before Iran developed a usable nuclear weapon. On this point, the Israelis disagree.

The critical question likely to be prompted by the agency’s report, which could be published as soon as Wednesday, comes down to this: How much closer is Iran to gaining a nuclear weapons ‘‘capability’’ — that is, the ability to produce a bomb on relatively short notice?