By CARA BUCKLEY

KEY WEST - The politically charged trial of six Cuban men accused of hijacking, set to start Monday in Key West, may prove a litmus test for the Cuban government's charges that the United States is too lenient on hijackers, an accusation that prosecutors are fighting hard to refute.

The March 19 skyjacking, allegedly accomplished with kitchen knives, tape and a hatchet, was followed by a second hijacking two weeks later, and a botched hijacking of a ferry a day after that. In response, Cuban leader Fidel Castro accused U.S. Interests Sections leader James Cason of encouraging dissent on the island and charged that Cuban hijacking suspects were treated as ''heroes'' by the U.S. government.

U.S. Attorney Marcos Jiménez swiftly retorted that the United States would punish any hijacker regardless of the person's native country. He also fought to stop any of the defendants from being able to post bond, but he failed despite three appeals.

The six men -- Alexis Norneilla Morales, 31, Eduardo Javier Mejía Morales, 26, Yainer Olivares Samón, 21, Neudis Infantes Hernández, 31, Alvenis Arias Izquierdo, 24, and Miakel Guerra Morales, 31 -- are charged with conspiracy, air piracy and interfering with a flight crew in the hijacking of a World War II-era DC-3 from Cuba's Isle of Youth to Key West.

The plane, escorted by U.S. fighter jets, landed safely and the suspects tossed their weapons out. None of the 31 passengers or the six crew members was hurt.

The defendants face life sentences if convicted.

The judge in the case, James Lawrence King, ruled in mid-November that the men's attorneys could not use Cuba's political or economic conditions as part of their defense.

The men didn't appear to be under threat of harm, he wrote, and did not try to leave Cuba legally.

Moreover, he said there was no proof that Cuba's living conditions necessitated a hijacking. ''Many Cubans live under such conditions, yet few hijack planes,'' King wrote.

King's decision angered Cubans in Miami, who said the limitation robs the trial of its context.

''We should give them the broadest and most expansive leeway in presenting the facts,'' said Joe Garcia, executive director of the Cuban American National Foundation. ``The very nature of hijackings usually has to do with a political message that people are trying to transmit.

ARGUING FOR CONTEXT

''If you that take away the political and economic conditions,'' he said, ``I don't know what other types of circumstances will exist.''

But others insist authorities are right to treat Cuban hijackers just as they would terrorists, especially given the anti-terrorist tactics the U.S. government has embraced following Sept. 11.

''The U.S. efforts to not politicize this is commendable, and shows a recognition for international cooperation on terrorists,'' said Ira Kurzban, a prominent immigration lawyer in Miami who is not involved in the case. ``And Cubans are going to look very carefully at how the U.S. tries the case in terms of getting a conviction.''

But Kurzban questioned whether South Florida is the appropriate location to try the case.

''You have to look at what steps they are taking to treat this as a serious prosecution,'' Kurzban said. ``The fact that they're trying these Cubans in the most heavily populated Cuban area in the United States suggests that they haven't gone out of their way to seek a less biased venue for the trial.''

There is a slim chance that the trial, rescheduled once, may be delayed yet again if defense lawyers can convince the court Monday that securing testimony from witnesses on the island is invaluable to their clients' defense.

Defense lawyers have been pushing to fly Cuban defense witnesses to the United States to testify. They said they were prevented in August from interviewing key witnesses on the island and held by armed guards in an airport lounge while prosecutors freely inspected the airport in Cuba.

A magistrate ordered the U.S. government to ask Cuba to send defense witnesses over to testify, causing prosecutors to be concerned that the witnesses were actually family members who would ultimately defect.

''To use the procedures of the federal criminal courts to allow other family members in Cuba to join these defendants in the United States would turn this process on its head,'' assistant U.S. attorneys Harry C. Wallace and John J. Delionado wrote in court papers.

HELP FROM CUBA

Regardless, defense lawyers learned that Cuba would allow witnesses to leave the island to testify only for the prosecution.

Ana Jhones, one of the defendants' lawyers, said in court papers that Castro had taken a ''personal interest'' in the case and met with crew members and returned passengers in a televised round-table talk.

She asked to have the case dismissed, a motion that magistrate judge John J. O'Sullivan denied, saying the U.S. did everything it could to get the Cuban nationals to testify.