Cracking down on the growing wave of Cubans fleeing toward South Florida, the government in Havana on Wednesday strengthened already tight restrictions on the construction and use of small boats.

A decree by the Council of Ministers said the illegal boaters are ``not only creating disorder and affecting fishing and navigation, but using illegally obtained materials to build their craft.

The decree made it illegal to build, use, repair, transport, dock or anchor any boat ``without proper authorization, saying that Cuba has ``the duty of impeding the illegal departures from the Communist-ruled island.

Authorities can seize the homes and cars of violators and fine them from 500 to 10,000 pesos -- $23 to $454 -- two to 46 months' salary for an average Cuban worker.

U.S. Coast Guard ships have intercepted more than 300 Cubans trying to sail to South Florida this month, bringing the year's total to 1,137, the highest since 1994, when Cuba allowed 35,000 people to leave unimpeded.

The Coast Guard has blamed 70 percent of the cases on smugglers who dash in from South Florida to pick up relatives and paying passengers, but Wednesday's decree was aimed more at domestic smugglers.

``In recent times there have been repeated violations of the established norms for owning and operating water craft . . . with the aim of using them for illegal departures, said the decree, published by the Communist Party newspaper Granma.

Cuba moved against the boat people, Granma added, based on a 1995 agreement with Washington that requires it to close its borders to illegal departures in return for 20,000 U.S. visas per year for an orderly exodus.

``Those who try to leave illegally violate our country's international commitments and promote disobedience and violation of the law, the decree said.

Cuba has been rife with rumors this summer that the government might again throw open its coasts to illegal departures. Three times since January, large groups of people have rushed to ports, believing they would be free to leave.

While the new restrictions were clearly aimed at Cuba's politically motivated boaters, they were also aimed at private fishermen who compete illegally with the state-owned commercial fishing fleets.

The Granma story complained that illegal fishing is costing the government $20 million a year, apparently most of it in illegal lobster catches. Although private citizens are banned from catching lobsters and private restaurants are banned from serving them, most private restaurants offer them.

Sport fishermen are also banned from selling their catch, although many coastal residents regularly spend their days catching large numbers of fish and selling them to neighbors and friends.

The few Cubans who own private boats -- mostly pre-1959 models or homemade craft with Russian engines -- are already required to notify authorities of any trips and to stay close to shore when they go fishing.

Until recently, about 20 young men in inner tubes would jump off each dawn from the eastern end of Havana's famed Malecon shoreside avenue and fish in the deep waters as they drifted west.

After a day of drifting they would swim ashore near the entrance to Havana Bay, some empty handed, some with big fish draped over the inner tube to keep them out of the reach of sharks.