WASHINGTON -- Determined to clamp down on exiles who enter Cuban territory illegally, the Clinton administration plans to declare most of the Florida coast a ``security zone'' where the U.S. Coast Guard may take special precautions.

U.S. officials said they will soon authorize the Coast Guard to ask boaters in all Florida ports minus the Panhandle if they are planning to go to Cuba, and to detain them or seize their boat if they plan to do so in violation of U.S. or Cuban law. The announcement is expected later this week.

The action is aimed at curbing unauthorized forays into Cuban waters by the so-called Democracia Movement, whose leader, Ramon Saul Sanchez, has eluded restrictions already in place in South Florida by setting out from ports in Central or Northern Florida, the officials said.

Sanchez called the measure ``obviously selective and discriminatory against the Democracy Movement because they don't prevent yachts from entering Cuba and because this measure is being implemented shortly before our next flotilla.''

The group had scheduled a flotilla for Monday to pay homage to 41 would-be refugees who died in July 1994, when Cuban government vessels rammed and sank the tugboat on which the Cubans were trying to flee. But because of the World Cup soccer championship, the Democracia Movement rescheduled their departure for 2 a.m. Saturday from Conch Harbor in Key West.

Sanchez said the U.S. government's ``attitude parallels that of the Cuban government to deny Cubans their humanitarian right under the United Nations declaration to enter their homeland.'' He also said it violated their constitutionally protected rights as citizens of the United States.

Legal questions

Administration officials said they are confident that such a procedure is legal, although some acknowledge constitutional issues involving prior restraint and the Fifth Amendment against self-incrimination.

The move is the second time this month that U.S. officials have sent a stern message to exile demonstrators, and comes amid growing evidence of people-smuggling from Cuba.

Last week, federal aviation officials warned Jose Basulto, the founder of Brothers to the Rescue, that he must respect international flight rules, even if his plane is intercepted by Cuban fighter planes.

``If intercepted by military aircraft from Cuba or the United States, you must comply with the instructions of the military aircraft,'' officials told Basulto, who piloted the only plane to escape an attack by Cuban MiGs on Feb. 24, 1996.

Four of Basulto's colleagues perished in the attack, which led to an abrupt hardening of U.S. policy toward Cuba. A United Nations investigation found that the shoot-down took place over international waters, but that Basulto's plane had briefly entered Cuban airspace.

Plans canceled

Basulto and two other exile pilots canceled their plans to fly near Cuban waters on Monday because of bad weather.

A White House official said Tuesday that the latest moves are aimed at protecting Americans who are traveling in authorized areas, including exiles who journey near Cuba to lay wreaths or demonstrate against the Cuban government.

``All of these measures are measures to enhance the safety of American citizens when they are conducting memorials or protests,'' said the official, who asked not to be identified.

They are also intended ``to prevent international confrontations,'' he said. ``Because the Cubans have shown they'll go outside of their territory after somebody they do not like.''

Expanded enforcement area

The new action will greatly expand the area in which the Coast Guard may intercede with boaters suspected of planning to visit Cuba illegally. Since March 1996, the Coast Guard's preventive steps have been limited to Florida ports and waters south of Fort Lauderdale.

Under that security zone, the Coast Guard seized Sanchez's boat in Key West on July 13, 1997, as he set out on a flotilla and refused to say he would not enter Cuban waters. But in January, officials said, Sanchez eluded them by setting out from Boynton Beach.

``If we have to go to Alaska to claim our rights, we will,'' Sanchez said Tuesday. ``And then it will be written in history that the United States tried to stop Cubans who differ in opinion with Castro from exercising their rights.''

Herald staff writer Ana Acle contributed to this report.