Marine Staff Sgt. Robert Stufflebeam yesterday was convicted on two counts of dereliction of duty for having had drinks in off-limits bars in Moscow, but acquitted on seven counts related to having had sex with Soviet women and lying about it.

A jury of eight Marines deliberated for 2 1/2 hours at the Quantico Marine Corps Base before convicting Stufflebeam on what defense attorney James Bagley called "the least serious of the charges against him."

"The most he will face is six months for each charge," Bagley said. The jury of five officers and three enlisted personnel is expected to decide the sentence today.

Stufflebeam, 25, of Bloomington, Ill., said afterward he was relieved by the verdict and added, "Not everything the Marine Corps allowed to be said about the Marines in Moscow was true. I had hoped they would back us up and not just give the Marines up to circumstances."

Earlier testimony criticized security at the U.S. embassy in Moscow as having been "extremely lax." Marines there were said to have indulged in black-marketeering and fraternization with Soviet citizens.

"The whole thing was pretty much a fabrication" of the Naval Investigative Services agents who conducted the investigation, Stufflebeam said.

Stufflebeam had been charged with three counts of having had contact and sexual relations with Soviet citizens, of failing to report the contacts and of having lied about some contacts. Had he been convicted, he could have faced up to 14 1/2 years in prison.

Asked how he felt about the Marine Corps now, Stufflebeam replied, "No comment." His defense had rested its case without calling any witnesses. "The government's witnesses won it for us," Bagley declared.

Government prosecutors yesterday introduced into evidence a signed statement by Stufflebeam that he had sex with two women on three occasions in Moscow in 1985 and that he had lied about it.

In the statement, Stufflebeam said he had sex in July 1985 with a dark-haired woman he orginally thought to be an Italian. He met her in a Moscow bar he knew to be off-limits to Marines, his statement said.

After the second sexual encounter with this woman, in September 1985, Stufflebeam became "alarmed," he said.

"After sex . . . she complimented me on the beauty of my eyes. She then asked if she could put some makeup on my eyes. I told her we could perhaps do that next time. When she said this, I became alarmed. I was concerned that she might be working for the KGB {Soviet secret police} and attempting to entrap me. I also thought that she might be sexually kinky, but in any regard, this spelled danger for me, and I did not want any further involvement.

"I thought that if I saw her the next time they would take pictures of me and try to blackmail me. I would never have allowed her to put makeup on me at any rate because that is not my thing," the statement said.

Stufflebeam also had sex with a "Soviet female" in her apartment in October 1985. He paid her 30 rubles and never saw her again, his statement said.

Stufflebeam stated several times that he was neither approached nor undertook to carry out any espionage activities. "I did not know of {Marine Sgt. Clayton J.} Lonetree's alleged involvement in espionage until I read it in the media," his statement said, referring to the Marine guard who served under him in Moscow. Lonetree was sentenced last month to 30 years' imprisonment for espionage in a sex-and-spying case.

Another guard Stufflebeam supervised, Cpl. Arnold Bracey, was initially charged in the case, but the charges were dismissed in June.

"I lied {to State Department officials and Navy investigators about the contacts} because I hoped to avoid the consequences of violating the . . . regulation regarding nonfraternization," Stufflebeam's statement said.

His defense contended that the statement, taken by NIS investigators in March, was not entirely voluntary and that the nationality and occupation of the women was never established by prosecutors.

Earlier, Navy investigator James Pender denied that he had struck Stufflebeam during a three-day interrogation in an Oceanside, Calif., motel in March of this year. He had "patted his knee" at one stage in order to calm Stufflebeam, whom he described as acting "violently," he said.

"He was one of the most aggressive individuals I have ever met," Pender said.

Another Marine, Sgt. Kenneth Kelliher, faces charges of failing to report contacts with Soviet citizens and lying; his court-martial has been ordered this fall. But the Marines have not decided whether to convene a court-martial for Cpl. Robert J. Williams, who was accused of false statements in the ongoing probe of espionage at the Moscow embassy.