WASHINGTON — Eight months after he narrowly survived an assassination attempt on the streets of Tehran, Fereydoon Abbasi, the nuclear physicist whom Iran’s mullahs have put in charge of the country’s Atomic Energy Organization, is presiding over what intelligence officials in several countries describe as an unexpected quickening of Iran’s production of nuclear material.

The selection of Dr. Abbasi earlier this year was itself a clear message to the West. As a university scientist, he was barred from traveling outside Iran by the United Nations Security Council because of evidence that his main focus was on how to build nuclear weapons, rather than power plants. But in recent weeks he has publicly declared that his country is preparing to triple its production of a type of nuclear fuel that moves it far closer to the ability to produce bomb-grade material in a hurry.

Filtering out the hyperbole surrounding recent proclamations about Iran’s tangible progress is always difficult, especially at a time when the country is determined to show that neither the Stuxnet computer worm, which crippled part of its nuclear infrastructure last year, nor Western sanctions have proved to be more than modest setbacks. Dr. Abbasi himself is rarely seen or heard outside of Iran.

But international nuclear inspectors and American officials say that all the evidence points to the imminent installation of centrifuges at an underground nuclear plant on a military base near the city of Qum. Iran revealed the existence of the plant in 2009, after learning that the United States and European powers were about to announce that they had discovered the complex, deep inside the Iranian base.