The Senate urged the government of Panama yesterday to oust strongman Gen. Manuel Noriega, pending an impartial investigation into allegations of murder, election fraud and corruption against him and others.

The Senate adopted, 84 to 2, a resolution urging that the government of Panama undertake an "impartial and independent investigation" of the allegations with the authority to make its findings public "without delay or fear of reprisal."

The resolution called on Panama to invoke existing provisions in its legal code to order Noriega and "other implicated officials to relinquish their duties pending the outcome of the independent investigation."

Noriega is the commander of the Panama Defense Forces, which rules the country despite a figurehead civilian government, and has been accused by the former chief of the general staff, Col. Roberto Diaz Herrera, of crimes.

Diaz Herrera accused Noriega and others of planning the assassination of former president Omar Torrijos, murdering and beheading of opposition leader Hugo Spadafora, rigging the 1984 election and taking millions in bribes and kickbacks, said Sen. Edward M. Kennedy (D-Mass.).

Before approving the resolution, the Senate rejected by a vote of 73 to 13 an amendment by Sens. Christopher J. Dodd (D-Conn.) and Daniel J. Evans (R-Wash.) to soften the resolution by not directly calling for Noriega's removal from office.

Dodd spent several days in Panama last week following violent protests that led to a government- imposed "state of urgency" and a suspension of constitutional guarantees.

Dodd, who offered the amendment on the advice of Panamanians, said the resolution would make it more difficult for the moderates, including some in the military, to press their case.

"If we make Noriega the sole and absolute target, we deny these elements room to maneuver," Dodd said. But Kennedy replied that "leaving out Gen. Noriega is like talking about the North Pole and leaving snow and ice out."

The defeat of the amendment also killed a proposed addition that would have reiterated Senate support for the Panama Canal treaties, which passed 10 years ago and ceded the canal to Panama.

The resolution calls on Panama to restore suspended constitutional rights, allow elected civilians to rule and keep the Defense Forces out of nonmilitary activities, take steps to provide credibility and confidence in elections and give full commitment to political pluralism. It also calls for free and fair elections, an independent judicial system and compliance with human rights.

Sen. Carl M. Levin (D-Mich.) and Dodd voted against the resolution.