The government prosecutor in the first Abscam bribery trial told the judge today that some tapes in the undercover FBI investigation show criminal activity by Sen. Harrison A. Williams Jr. (D-N.J.).

It was believed to be the first public pronouncement by a Justice Department attorney of alleged criminal culpability by Williams. Though the statement by Thomas P. Puccio was made out of the hearing of the jury, defense attorneys called it a "cheap shot," and Williams' attorney said it was "outrageous" because the senator has not been charged in the Abscam cases. w

George Koelver, Williams' attorney, said in a telephone interview from New Jersey tonight that "it is outrageous that Mr. Puccio continues to make unwarranted, unfounded allegations concerning Sen. Williams. Sen. Williams has committed no crime nor has he been charged with commission of any crime."

Puccio declined to say why he made the reference to Williams.

The prosecutor made the comment when he complained about defense attorney Richard Ben-veniste's cross-examination of Melvin Weinberg, the convicted con man who was an undercover informant for the FBI and is a key witness in the trial of Rep. Michael O. (Ozzie) Myers (D-Pa.) and three codefendants.

Ben-Veniste quoted from transcripts of taped telephone conversations in which Weinberg urged an unidentified middleman to have an unnamed politician "come on strong." There also was discussion of the politician "going in like a tiger, not like the regular guy we know."

During the afternoon recess, Puccio complained that the quotations were taken out of context. The whole conversation, he said, "would show Errichetti [defendant and Camden, N.J., Mayor Angelo Errichetti] participating in a crime with Sen. Williams."

When the Abscam story broke in February, news accounts said Williams was under investigation for allegedly taking stock in a titanium mining venture in return for helping undercover agents posing as businessmen get government contracts for selling the metal. Justice Department officials have told the Senate Ethics Committee that they expect to decide by Labor Day whether to seek an indictment of Williams.

Ben-Veniste's use of the quotes was part of the defense's efforts to undermine Weinberg's credibility. Defense lawyers assert their clients had no intention of violating federal bribery laws, but were tricked into acting out a role scripted by Weinberg to further his own ends.

During today's cross-examination, defense attorneys elicited from Weinberg:

That he was paid $3,000 a month by the FBI, and continues to be, and has paid no income taxes for the last two years. He also acknowledged receiving a $25,000 "kickback" from Errichetti in an unexplained transaction, and has received $100,000 advance on a book he plans to write with Newsday editor Bob Greene.

Weinberg's total payments since he became a government informer in 1969 -- nearly a decade before Abscam -- have totaled about $140,000, according to Puccio.

A history of his previous confidence schemes, including ventures in which he swindled a cousin out of $50,000, tried to franchise the use of his phony offices to other con men and sold phony contracts in an Indian gold mine.

Weinberg said the Indians had first conned him into buying the contracts but that he quickly recovered and sold shares to others for $1,000 each.

He also said that when he was young, and his father was in the glass business, he used to break store windows with a slingshot.

Ben-Veniste apparently learned of Weinberg's past from a book outline Greene submitted to publishers.

Defense attorneys told the judge last week that they planned to "blow Weinberg out of the witness chair," but he was still there at the end of today's session. He answered hostile questions in a low, even voice, raising it once to say "that's a lie" when Ben-Veniste suggested that he had deliberately stopped his tape recorder at crucial moments in conversations with the defendants.

He did agree with Ben-Veniste's characterization of Abscam as a "con man's dream" because the FBI secured the cooperation of the Chase Manhattan Bank. The undercover agents, who posed as representatives of a mythical Arab sheik, told their visitors that the sheik had $400 million in a Chase account.

At another point, however, Ben-Veniste uncovered information that raised questions about how Abscam fooled anyone. Weinberg's business card showed that his firm had connections in "Zurick," Switzerland.

When Ben-Veniste asked him if Zurich was misspelled, Weinberg said he didn't think so.