The Spanish press today defied strong government pressure and published an extensive, confidential report dealing with the circumstances of last month's abortive coup that was read to a closed door session of Parliament last night by the defense minister.

The defiance signaled the end of a honeymoon relationship between the press and the government in the immediate aftermath of the coup attempt and contrasted with a manifest caution among politicians who appear fearful of antagonizing the military.

Defense Minister Alberto Oliart's hour-long statement to Congress contained few surprises other than the disclosure that investigations into the seizure of Parliament on Feb. 23 by a group of insurgents included the interrogation of a number of unnamed civilians. Exhaustive details of the plotting among officers commanding key units had already appeared in the press here.

But in line with a low profile maintained by the government since the attempted coup, the ruling Union of the Democratic Center Party overrode objections from the communist and socialist opposition and ordered that the minister's report be heard in closed session. After the meeting was over, journalists obtained tape recordings of the statement from members of Congress and newspaper editors withstood a barrage of official pressure seeking to keep the statement secret.

Before the meeting was held, journalists were barred from entering the Parliament building. Television and radio microphones installed in the 350-member debating chamber were sealed before the defense minister began his report. The recording of the speech was allegedly carried out by a group of opposition congressmen who objected to the unprecedented secrecy.

Defending its decision to publish the leading madrid newspaper El Pais said in an editorial: "the sole danger of such secrecy . . . is that the general public will receive a confused and manipulated version of what it was prevented from learning in a clear and direct manner."

El Pais reported that its editor had received a telephone call from an Army major who, on behalf of the Defense Ministry, ordered that the leaked coup report be suppressed. Earlier both the ministry and the prime minister's information office had issued statements requesting that the secrecy of the Congress session be observed by the media.

The pressure on the press last night was the latest in a series of moves against press freedoms in the post-coup period that are causing concern among Spanish journalists. A troublesome sign is an apparently widespread conservative attitude that holds the press at least partially responsible for the coup because of its allegedly sensationalist reporting of Spain's political transition process.

Typical of such reactions was one by the press officer of the ruling UCD party who, in a newspaper interview Monday, said the press had to take its share of the blame for the public lack of confidence in the government that could have been instrumental in stirring military ambitions. Spokesman Juan Diez Nicolas said the role of the press had "not been beneficial" to the consolidation of democracy.

Illustrative of an apparent restrictive climate was a terse communique issued yesterday by the defense ministry press office, which is run by Army officers, saying that the office was the sole official source dealing with information about the coup and of its aftermath. The statement said all official sourcing should reveal the name and rank of the informant.