TROMBAY, India — Deep inside India's most secretive research center, sheltered between the Trombay Hills and a backwater cove of the Arabian Sea, R. Chidambaram leaned against a 50-foot conference table one recent morning and was astonishingly open about the work going on in the strange, unmarked buildings nearby.

It was here, the center's director said, that scientists fashioned the fuel and components for India's first nuclear bomb--the "peaceful nuclear explosion" that it detonated 107 yards beneath the Rajasthan desert to gain unofficial entry to the world's nuclear club in 1974.

And it is here, he confirmed, that scientists continue to work day and night processing and stockpiling enough weapons-grade plutonium to alarm nuclear weapons analysts from Washington to Moscow--so much so that both capitals have launched unprecedented diplomatic efforts to curb nuclear proliferation both here and in India's western neighbor, Pakistan.

In short, Chidambaram, the head of India's Bhabha Atomic Research Center, made it clear that his sprawling seacoast facility--better known by its acronym, BARC--is the brain trust of South Asia's growing nuclear arms race.

"I can understand the non-proliferation concerns of the developed countries," the soft-spoken South Indian solid-state physicist said firmly when asked why India insists that his facility remain so shrouded from the major nuclear powers.

"But then, we are not one of these small developing countries on the map you just tick off like that. . . . What technology don't we have?

"India is not just another one of those countries. India is the one country that has the technology. And we didn't rely on clandestinely supplied or stolen technology to achieve it."

They were rare moments of candor from one of India's long-secretive nuclear elite. But perhaps even more surprising than Chidambaram's admission of India's nuclear capability was his audience that day: two American journalists who had been granted almost unprecedented permission to tour the top-secret facility and interview its director.

The timing of the tour and the apparent new policy of nuclear transparency hardly appeared a coincidence, though. Earlier last month, Indian Foreign Secretary Jyotindra Nath Dixit traveled to Washington for three days of high-level talks, largely centered on the nuclear issue.