Delegates from East and West reached broad agreement today on ground rules for a conference on detente and human rights after a hectic round of bargaining and late-night talks.

More than six weeks after the president meeting began, only a few relatively technical details remain to be solved. Barring last-minute surprises, delegates said, they expect the final package, which includes major concessions from both sides, to be formally approved in the next few days.

U.S. officials expressed confidence that the agenda and organizational framework for the main meeting in the fall would allow full review of implementation of the controversial human-rights provisions of the 1975 Helsinki agreement. In the present preliminary talks, the Soviet Union's aim has been to try to restrict opportunities for debate as much as possible.

The path to an agreement was opened by what amounted to a softening in Western insistence that there should be no fixed time-limit to the talks. Delegates now seem agreed that the conference should not proceed beyond the middle of next February.

Earlier opposition by the United States and other Western contries to Soviet demands for a cutoff date was based on the belief that this might lead to a filibuster over human rights.

According to the latest draft, which is likely to be accepted, the meeting will begin Sept. 27 and attempt to complete its work by Dec. 15. If this proves impossible, it will resume Jan. 15 for "up to one month."

Some delegates claim that the next sentence - a statement that the conference will end by agreeing on a concluding document and a time and place for a future meeting - creates an ambiguity. But the consensus is that it would be almost inconceivable for the talks to continue beyond the middle of February.

"That should give us plenty of time for us to talk about human rights. Of course, it's no guarantee that the Soviet Union will listen to what we have to say, but that was impossible to insure anyway." a U.S. delegate remarked privately after yesterday's session.

In return for giving ground on the cut-off date, American delegates claim, they achieved their two other main aims:

There will be an orderly framework for the talks, with discussion of implementation preceding discussion of new proposals.

There will be further meetings in the future to examine progress achieved since the Helsinki declaration.

For its part, the Soviet Union has been forced to concede the establishment of committees, including one on humanitarian questions, but has succeeded in limiting the amount of time they will be able to operate to around eight weeks.

It has also managed to avoid being dragged into long semi-permanent negotiations of the kind that preceded the signing of the Helsinki agreement.

The main gain for the neutral and nonaligned countries is a commitment that the process of detente, involving multilateral negotiations on the basis of consensus, will be continued in the future.

Some delegations - notably the Dutch. British and Romanians - appeared unhappy about the final formulation of the cut-off date and would have preferred a more flexible approach. But other delegates said it would be difficult for them to create obstacles without seriously disrupting the talks.

Finishing touches to the final draft were being made at an informal meeting of some 15 delegates that continued late tonight. Western delegates said they believe that the body would be able to present its conclustons to a plenary meeting for formal approval Friday.

Under the agreement, separate committees will be established to consider each of the main elements of the Helsinki declaration: security in Europe, economic cooperation and human rights. There are also to be two subsidiary committees, on future follow-up and on cooperation in the Mediterranean.

Work in committees is to begin two weeks after the opening of the conference. The U.S. delegation is likely to include compliance with the Helsinki declaration.