NEW YORK (AP) _ A Marine sergeant accused of spying for the Soviet Union said he cooperated with a Soviet agent because he was interested in ''knowing what the KGB wanted to know,'' but found himself in over his head, according to a record of his questioning released by one of his lawyers.

The sergeant, Clayton J. Lonetree, allegedly was approached late in 1985 when he was a guard at the U.S. Embassy in Moscow and continued to meet a Soviet agent when he was transferred to the embassy in Vienna last year.

He made increasingly serious admissions during interrogations by U.S. naval intelligence agents from Dec. 24 through Dec. 29, 1986, the record showed.

The record consisted of 20 pages of statements signed by Lonetree and three pages of the agents' summaries of statements Lonetree allegedly made in the latter stages of questioning. He would not sign the summaries and asked for a lawyer, the summaries said.

The interrogation showed a man actually spinning out a fantasy or responding to coercion by the investigators, according to William Kunstler, one of Lonetree's civilian lawyers who released the record.

''I don't think you can tell where his (Lonetree's) fantasy world ended and reality began,'' said Ronald Kuby, another of Lonetree's lawyers.

Lonetree, 25, who describes himself as being of American Indian descent, said, according to the documents: ''I guess some of my actions were based on hatred for prejudices in the United States ... because of what the white man did to the Indian.

''What I did was nothing compared to what the U.S. government did to the American Indian 100 years ago.''

Then, in his own handwriting, he added to the typed statement: ''But I still have a great love for my country.''

Early in the interrogation, Lonetree said that an affair with Violetta Seina, a Russian employed as a translator in the embassy, led to meetings with a man named Sasha, purportedly Violetta's uncle.

After the third meeting, Lonetree said, ''I knew Sasha was KGB, but I was careful about what I was saying. I didn't report this meeting because I was interested in knowing what the KGB wanted to know,'' the documents show.

He said he received $3,500 for information. With the money, he said, he bought Violetta a $1,000 dress, Sasha a silk tie and treated his Marine buddies to meals and beer.

Lonetree admitted that he failed to inform authorities, as required, of any of his contacts with Violetta, Sasha and, later in Vienna, with an agent named George.

Lonetree said he had also failed to divulge earlier that Sasha asked him to place a bug in the U.S. ambassador's office in Moscow. He did not do so.

He also said Sasha made him write in his own hand and sign a statement that said, ''I am a friend of the Soviet Union. I will always be a friend of the Soviet Union and will continue to be their friend.''

Naval intelligence agents David Moyer and Thomas E. Brannon said that Lonetree admitted stealing three documents marked top secret at the embassy in Vienna and hiding them in a drain pipe on the roof of the Marine quarters. He later stole 120 secret documents from a burn bag, they said.