WASHINGTON (AP) _ President Bush, concerned about reports of a growing nuclear arms race between India and Pakistan, plans to press India's prime minister to curb his government's nuclear program.

Bush intends to raise the subject Friday with Prime Minister P.V. Narasimha Rao in New York, where both will be attending a U.N. Security Council session.

Their meeting follows this week's visit to New Delhi by Ronald Lehman, director of the U.S. Arms Control and Disarmament Agency, to gauge India's views now that it has lost the patronage of the Soviet Union.

The United States, which has long lacked leverage on the populous Asian country, has recently sensed that the demise of the Soviet Union is changing India's position on the nuclear subject, officials say.

''They don't want to be left isolated,'' said one U.S. official.

At the same time, U.S. intelligence reports are ringing alarms about an intensified competition between the two Asian giants, who have fought three wars since they gained independence in 1947.

CIA director Robert Gates testified recently that the United States was worried about the potential for nuclear conflict between the two countries, both of which are also developing ballistic missiles.

As a first step, Bush intends to urge India to attend a regional conference with Pakistan, Russia and China to discuss a nuclear-free zone in south Asia, officials said.

Despite lobbying by high-level British and U.S. envoys, India has so far been noncommittal about the conference, which the United States wants to convene this spring, say U.S. officials.

''We are seriously studying the proposal,'' said Indian Embassy spokesman Gopalakrishnan Jagannathan.

But, he added, India feels threatened by its two powerful neighbors - Pakistan, which he said has a clandestine nuclear weapons program, and China, which is an acknowledged nuclear power. India, he added, doesn't have nuclear weapons.

That's not what U.S. experts believe. India, which has an extensive network of nuclear power plants, set off a nuclear test device in 1974 and had since been developing weapons capability.

''There's no doubt about it,'' said Gary Milhollin, a private expert on nuclear weapons proliferation who directs the Wisconsin Arms Control Project.

He said India is believed to have several dozen plutonium-based fission bombs, while Pakistan probably has up to a dozen uranium-based fission bombs.

Pakistan says it wants to attend the U.S.-proposed regional arms control conference and would be willing to sign an international treaty governing the spread of nuclear weapons if India does.

U.S. officials say the ideal solution would be a nuclear-free zone in sought Asia. Short of that, they say, the United States has sounded out China and the former Soviet Union about offering assurances to India that they would not launch a nuclear attack.

But India has said it doubts the value of such assurances.