U.S. Senator John Kerry is wrapping up a three-day visit to India, where he voiced cautious support for a controversial nuclear energy deal now under discussion by Washington and New Delhi. Kerry said the deal to share U.S. civilian nuclear technology with India could be an important step for nuclear non-proliferation.

The United States has sought to isolate India's nuclear program for decades, angered at the country's decision to develop and test nuclear weapons, and at its long-standing refusal to sign the global Non-Proliferation Treaty, or NPT.

In July, Washington reversed its stance, agreeing in principle to provide nuclear fuel, technology and equipment for India's civilian energy program. Before that happens, the deal must be ratified by Congress.

On a three-day visit to India, Senator John Kerry, a leading member of the minority Democratic Party who ran against President Bush in the 2004 election, gave his cautious support to the plan. He says it makes sense to bring India's civilian nuclear program under the supervision of international nuclear inspectors.

"In principle, I support this," Senator Kerry said. "In principle, I think there is a great gain, a positive gain, for India, for the United States, for the global community, with respect to oversight that doesn't today exist. And it is better to take three-quarters of the program and get it under there, providing you're not undermining the larger, strategic goal of the NPT itself."

Before the deal is finalized, the United States and India must first agree on the terms of several complex regulatory issues, including the separation of India's civilian and military nuclear programs, nuclear safeguards and the start of international inspections at India's nuclear facilities.

U.S. Undersecretary of State Nicholas Burns is expected to visit India later this month for further discussions on the issue.

With a rapidly expanding economy and a population of more than a billion people, India says it needs improved nuclear technology to meet its growing energy needs. Critics, however, charge that such a deal could fuel an arms race with India's historic enemy and nuclear rival, Pakistan.

The deal could also complicate efforts by the U.S. and the European Union to counter Iran's nuclear program, which they fear is intended to build nuclear weapons. Iran insists that it wants nuclear technology only for civilian use. Kerry says that his meetings with senior Indian officials included discussions of the deal's broader implications.

"It is important to view it in its bilateral context," he said. "But it is also, by definition, something that has an impact that is broader than bilateral, and you have to also take into account those considerations, particularly at this moment with Iran."

Kerry visited India as part of a 12-day trip that includes stops in Afghanistan and Iraq to assess the U.S.-led war on terror.

On Saturday, he is scheduled to go to Pakistan, where he is expected to tour regions devastated by the October 8 earthquake in Kashmir.