The House ethics committee recommended that Rep. Mario Biaggi (D-N.Y.) be expelled because he is guilty of "criminal conduct of a most serious nature going to the heart of his representational responsibilities."

In a 148-page report on its investigation of Biaggi released yesterday, the panel concluded that "expulsion is the only sanction appropriate to the violations" of federal law for which the veteran Democrat was convicted by a federal jury last September.

The ethics panel, formally the Committee on Standards of Official Conduct, unanimously recommended last Thursday that the House expel Biaggi, who could become the second House member to be expelled on corruption charges. Three others were expelled for treason for supporting the Confederacy during the Civil War.

Biaggi, 70, has vowed to fight, arguing that the House should not pass judgment on him until his appeal is decided. Acquitted of more serious bribery and conspiracy charges, Biaggi was sentenced to 2 1/2 years in prison and fined $500,000 on charges of receiving illegal gratuities, obstruction of justice and a related charge of "illegal trafficking."

The committee's expulsion recommendation, which can be brought to the floor at any time by Chairman Julian C. Dixon (D-Calif.), may be voted on as early as Wednesday.

The committee report contains a detailed examination of how Biaggi's conviction on three felony charges constitutes violations of House rules. The panel found that Biaggi brought discredit on the House, accepted "impermissible gifts from a person or organization with a direct or indirect interest in legislation," and failed to disclose gifts of $250 or more on his financial disclosure reports.

Biaggi was convicted on charges relating to free vacation trips he accepted from former Brooklyn Democratic leader Meade Esposito in return for Biaggi's aiding a ship-repair firm that owed Esposito's insurance company almost $300,000.

The ethics panel report included a transcript of a Dec. 17 committee hearing in which Biaggi and his attorneys argued forcefully that based on previous House cases, the ethics committee should recommend reprimand rather than expulsion for the New York lawmaker.

Biaggi, who had declined invitations to appear before the panel during its earlier deliberations, made a lengthy appeal to the committee, arguing that his trips to a Florida spa and a Caribbean island at Esposito's expense were nothing more than "hospitality" stemming from a decades-long friendship and that his actions on behalf of the ship-repair firm represented the normal work of a congressman seeking to protect jobs in his state.

Biaggi also defended himself against the obstruction of justice charge, which was based on a tapped conversation he had with Esposito immediately after he was interviewed by the Federal Bureau of Investigation. The jury determined that Biaggi was coaching Esposito on how to answer inquiries about the trips to the Florida spa. Biaggi told the committee that the jury was wrong and that he was merely attempting to "refresh {Esposito's} memory."

Biaggi also warned his colleagues that they could easily be subject to similar criminal charges. "We could all be vulnerable," Biaggi said at the hearing. "All they need is a focus, whether it be a golf trip, whether it be a convention, whether it be a stay at a hotel."

Chief counsel for the ethics committee, Ralph L. Lotkin, disputed Biaggi's interpretation of those events, arguing that Biaggi had committed "a breach of the public trust."

"There was an effort to obstruct justice by having Meade Esposito not truthfully relate to the FBI why the congressman went to the spa and to the islands in 1984 and 1985," Lotkin said. "There clearly is a relationship between the gratuities and the official duties and to say the obstruction somehow is unrelated boggles my mind."