After two days of intense negotiations, the United States said Friday it had failed to reach agreement with India on the separation of its civilian and military nuclear programs.

The White House is still hoping for an accord before President Bush visits New Delhi next week, but said the success or failure of the trip does not hang on the nuclear agreement.

"We would like to get it before the trip," national security adviser Stephen Hadley said. "If we can, great. If we can't, we'll continue to negotiate it after the trip."

Bush departs for India on Tuesday and his official schedule there begins on Thursday. The president also will visit Pakistan before beginning the long flight home on Saturday.

Undersecretary of State Nicholas Burns spent two days in difficult talks in New Delhi and returned home Friday to report on the negotiations.

"We're making progress, but we're not yet there," Hadley said at a briefing on Bush's trip. "The Indians, hopefully, will have an opportunity from their end to see where we are, and we would expect those negotiations will continue by phone, document and the like, probably up to the president's visit."

Both sides want an agreement, Hadley said, but "it's important to have a good agreement that works for the Indians, works for the United States, will be acceptable to our Congress and to the Nuclear Suppliers Group" of nations that export nuclear material.

The nuclear cooperation agreement has been billed as the cornerstone of a warming U.S.-India alliance.

There is opposition in India to opening the country's secretive nuclear industry. In the United States, critics argue that the administration is rewarding bad behavior since India has refused to sign the Nuclear Nonproliferation Treaty and defied the world by conducting nuclear weapons tests in 1998. Any agreement faces stiff opposition in Congress.

Asked what was blocking an agreement, Hadley said: "It's just getting some clarification from the Indian side about what's in the civil side and what's on the military side. Not only in terms of what exists now, at this time, but what are going to be the ground rules going forward. There's a lot of technical aspects to it."