Troops sealed off a harbor in northeastern Cuba on Wednesday to keep rowdy crowds from witnessing a standoff between Cuban forces and a dozen men and women apparently bent on fleeing the island in a boat, residents of the area reported.

About 1,000 people gathered around the Puerto Padre harbor at the start of the incident Tuesday, with some chanting ``Freedom! and others using dinghies to deliver food and water to the occupants of the stranded vessel, the witnesses said.

The unusual gathering (assemblies not arranged by the government are rare in Cuba) marked the third time this year that large crowds have rushed to Cuban ports amid reports of illegal escapes toward South Florida. Both the effort to keep crowds away and the wait-and-see posture adopted by the government appeared designed to keep an embarrassing incident from escalating into violence.

Cuba's government-controlled media did not mention the incident, but four Puerto Padre residents telephoned by The Herald gave detailed and matching accounts, asking only to remain anonymous for fear of reprisals.

The witnesses said the dozen men and women were trying to flee Puerto Padre late Monday or early Tuesday aboard a locally registered 21-foot boat when their motor broke down and they anchored in the middle of the bay to make repairs.

Cuban troops approached the boat Tuesday but the group refused to surrender and continued fixing the motor in full view of the town of about 10,000 people, they said.

``The whole town had lined the harbor to support the group yesterday [Tuesday] by 1 p.m., but everyone went home at night, and this morning the soldiers had closed off all the roads, said a woman who lives near the harbor.

``There's been no violence, no. But the police had to be on their best behavior, because people were really angry, said a man who said he had been drawn to the dock area Tuesday by the shouts of ``Freedom!

One woman said that as of 3 p.m. Wednesday, she could still see the would-be refugees aboard the boat, anchored in the bay but watched from a distance by ``lots and lots of police and men in military uniforms, either soldiers or border patrol troops from the Ministry of the Interior.

Western diplomats in Havana said they had received similar reports on the incident from Puerto Padre residents but had no way to confirm them.

The Puerto Padre incident, the third since January in which large crowds have rushed to Cuban ports, underlined the growing desire among Cubans to escape the island's economic chaos and political controls.

Interior Ministry paramilitary police were forced to close access to the port of Cabanas, about 30 miles west of Havana, early this year when about 2,000 people quickly gathered there amid rumors that the government was about to allow several ships to sail for South Florida.

In early June, Cuban troops dispersed a crowd of about 1,500 people who rushed to the port of Gibara, 520 miles east of Havana, amid rumors that the port would be opened to unrestricted departures.

Similar rumors at that time swept Guantanamo, the southeastern city 10 miles from the U.S. Naval Base, following reports that President Fidel Castro would soon allow anyone to leave Cuba through the base.

While all the incidents ended peacefully, Cuba analysts have expressed concern that the unusual gatherings might eventually spin out of control and spark violent confrontations between government forces and groups trying to leave the island.

The Cuban authorities' apparent wait-and-see posture toward the dozen people trying to escape Puerto Padre contrasted with the U.S. Coast Guard's reaction to the attempts by six Cubans to reach Surfside last week.

Guardsmen sprayed those Cubans with water and pepper spray in an attempt to block them from reaching land and automatic safety, sparking an outcry and street protests among Cuban exiles in South Florida.