Defense Secretary Caspar W. Weinberger left for Washington today amid Spanish assertions that his encouragement of this country's full participation in NATO had made little impact on the new Socialist administration.

Defense Minister Narcis Serra told the national news agency EFE after Weinberger's departure, "We are neither further from nor nearer to NATO, just better informed. We are exactly where we were" on the issue.

Officials said Spain's position remained unchanged since December, when Premier Felipe Gonzalez took office and ordered a freeze on negotiations to join the North Atlantic Treaty Organization's military command structure. The Gonzalez government said then, and repeated during Weinberger's two-day stay, that Spain was firmly in the western camp but was restudying its NATO membership.

The Socialist position is that the entry into the alliance last June under the previous center-right administration was hurried and did not take sufficiently into account Spain's defense interests. The premier's office said that in his meeting with Weinberger, Gonzalez had underlined that the existence of "a good defensive system in the West was a guarantee for Spain" and the region. The statement made no mention of NATO.

The officials said Weinberger had been told in his meetings with Gonzalez, Defense Minister Serra and Foreign Minister Fernando Moran that the new administration was engaging in a broad study seeking firm guidelines for a national defense policy. "This has never been properly undertaken before in Spain," said a senior government aide.

Weinberger alluded to this during a speech last night when he expressed hopes that "the benefits and wisdom" of staying in the alliance "become increasingly clear as you proceed with your security review."

Among the Spanish concerns said to have been expressed were: definition of a Spanish role within the alliance, focusing on the defense of the entry to the Mediterranean and perhaps involving creation of a new NATO command; use of the membership issue as a lever in drawn-out negotiations to join the European Community and in the stalemate over Spanish claims to the British colony of Gibraltar; and guarantees for Spain's North African enclaves of Ceuta and Melilla, both claimed by Morocco.

The Gonzalez government reportedly asserted that it did not put a high priority on the NATO issue and that Spain did not feel pressure to resolve its status within the alliance. An official said Weinberger was told there was no fixed date for fulfilling an election pledge of a referendum on membership but that the plebiscite had not been shelved. Gonzalez said at a press conference last week there would be no referendum this year while East-West tensions persisted.

"There are many more pressing problems than NATO," said a senior official, alluding to domestic issues. The more immediate security issue was believed to have been resolved by a protocol signed last month paving the way for a Spanish ratification next month of a five-year U.S.-Spanish defense agreement. An addendum provides for a revision of the agreement should Spain leave NATO.

While the Gonzalez government placed a low priority on the NATO issue, recent polls indicate that more than 60 percent of the respondents want not only to withdraw from NATO but also to close U.S. bases.

"There is strong neutralist and nonaligned bias in Spain," said the official, "and we've been telling the Weinberger team that, too."