Despite persistent denials, two rebel leaders and a pair of convicted drug smugglers are the latest to testify to Congress that the U.S.-backed Contras used cocaine profits to help fund their fight against the Nicaraguan government.

In the fourth day of Senate hearings on narcotics traffic this week, George Morales and Gary Betzner were the star witnesses for the Foreign Relations Committee's Subcommittee on Terrorism and Narcotics. Both convicted smugglers described how they used cocaine proceeds to assist the Contra guerrillas.Their sworn statements were made only hours before ABC News reported Thursday that the same pilots and aircraft involved in flying loads of drugs into the United States from 1983 to 1986 were used in a covert U.S.-Israeli network supplying arms to the Contras even before the notorious Iran-Contra operation.

"I'm convinced beyond a reasonable doubt about what was happening," said Sen. John Kerry, D-Mass., at the conclusion of Thursday's hearing. Kerry, who has spent two years leading the subcommittee investigation of the Contra-cocaine connection, said, "I believe there was narcotics flowing back and forth as part of an abberation in the entire network that had been created down there."

He noted caustically that "a clandestine network that can work with impunity to take weapons out of the (United States) ... can use that impunity to bring other things back in."

Morales, serving a 16-year prison term on drug charges, testified that he gave "between $4 million and $5 million" in weapons and several planes to the Contras over a two-year period when Congress had banned U.S. assistance.

Morales said his relationship with the rebels began in the spring of 1984, when he was approached by three senior Contra officials soon after he was indicted in the United States.

The Contras Adolfo Chamorro, Octaviano Cesar and Marcos Aguado said they would "take care of my indictment" through contacts in Washington in exchange for assistance, Morales said. He continued smuggling for more than two years before he was captured because he thought he was "being protected," he added.

"They wanted planes, money, boats there was a list of items," Morales testified. "In order to carry out their objectives, I needed pilots and I needed help with my legal situation."