A convicted marijuana smuggler told Congress Tuesday of an offer eight years ago by then-Panamian ruler Omar Torrijos and an aide Manuel Antonio Noriega to use an island off Panama for drug shipments.

But the smuggler, Michael P. Vogel, said he and an associate rejected the offer because the two Panamanian leaders "were being extremely, extremely greedy."Vogel said he traveled to Panama in late 1979 or early 1980 with a Cuban associate who was interested in establishing a shipment base for drugs. They met with Torrijos and Noriega, who now is Panama's military ruler and under U.S. indictment on drug charges, for about three hours, he testified.

"They wanted `x' amount of dollars for each pound of marijuana," or about $100,000 per trip, Vogel said, an amount out of proportion for the small shipments he had planned.

Vogel also described for the Senate Foreign Relations narcotics subcommittee the elaborate methods he and other smugglers developed over his 14-year career to evade U.S. drug interdiction efforts.

The methods included intelligence collection, sometimes using officials inside federal agencies, and electronic countermeasures to detect law enforcement vessels. Smugglers would obtain the radio frequencies officials used for communications and even had the frequency of Air Force One, the president's plane, at one point, he testified.

Vogel is serving a 121/2-year sentence for his activities, and he testified under oath on the second day of a weeklong continuation of the panel's probe of the drug trade.

On Monday a former U.S. ambassador told the panel that Reagan administration officials helped a Honduran general involved in a drug-financed plot to assassinate that country's president get a lighter sentence.

Francis McNeil, former U.S. ambassador to Costa Rica, told a Senate subcommittee Monday that top U.S. officials interceded on behalf of Honduran Gen. Jose Bueso Rosa because he had helped the administration's program of aiding the Nicaraguan Contra rebels.

Among those who interceded on Bueso Rosa's behalf was Assistant Secretary of State Elliott Abrams, the administration's top official in charge of inter-American affairs and a prime architect of the Contra policy, McNeil said.

McNeil said Bueso Rosa was charged in the United States with taking part in a plot, financed by drug trafficking profits, to assassinate Honduran President Roberto Suazo in 1984.

Two others involved in the unsuccessful plot received long sentences, but Bueso Rosa got off with a five-year term after the U.S. officials interceded for him, said McNeil.

At least one reason for the intervention was the general's "past usefulness to the Contra program," he said.

The State Department censored part of McNeil's testimony that detailed how Abrams at one point in 1986 urged that Noriega be pressured from power because of his drug-related activities.

While the testimony was blacked out on copies of McNeil's statement, Sen. Alfonse D'Amato, R-N.Y., referred to it and read part of it in open session.