HAVANA -- In a high-stakes sprint, a growing number of Cubans are fleeing the island aboard speedboats that zip back and forth across the Florida Straits, stirring angry authorities in Havana to promise ``severe measures.''

Cuba deplored the ``inhuman'' smuggling last week and urged Washington to send back Cubans who reach U.S. shores -- rather than embrace them.

President Fidel Castro recently demanded life prison terms for those convicted of the ``really serious, risky and repugnant business'' of trafficking.

In the past week, at least 167 Cuban and Haitian refugees have landed on South Florida's shores. Most of the Cubans allege that Cuban coast guard vessels have not bothered to intercept their voyages, even when they are in plain sight.

A desk clerk at a Miami Beach hotel alerted police Thursday night to 26 Cuban refugees who had just been dropped off by a fishing boat behind the hotel.

The Cubans -- 11 men, eight women and seven children -- landed behind the Golden Sands Hotel on Collins Avenue, Miami Beach Police said. Witnesses said they saw the Cubans being dropped off by a gray fishing boat, about 20 feet long, which then sped off.

U.S. authorities say it is as difficult to stop the trafficking of Cuban immigrants as it is to halt narcotics smuggling. So far, though, they say the speedboat phenomenon has not yet gotten out of hand.

``Our sense is that this is episodic, there has been an upsurge, but some of this [smuggling] is beyond the control'' of the Cuban government, said Michael Ranneberger, coordinator of the State Department's Office of Cuban Affairs. ``We do have a big concern about alien smuggling, and we're trying to interdict it and prosecute smugglers.''

U.S. smugglers detained

Cuban authorities have told officials at the U.S. Interests Section -- the American diplomatic mission in Havana -- that 15 smugglers based in the United States are under arrest in Cuba. Two of them are U.S. citizens, and the rest appear to be U.S. residents.

American diplomats have not been allowed to visit the detainees, whose identities were not available.

In a weekly briefing Thursday, Foreign Ministry spokesman Alejandro Gonzalez condemned the smugglers as ``unscrupulous'' people who make ``thousands of dollars'' for each Cuban they pluck off the island. He said lives have been lost in bungled crossings.

``Cuba has the intention of adopting severe measures against these traffickers and it expects the United States to do the same,'' Gonzalez said.

He cited a ``notable increase'' in the number of speedboats arriving.

Nighttime provides `cover'

At the Hemingway Marina on the western outskirts of Havana, manager Amado Polo Hernandez said speedboats arrive at night and usually far from populated areas.

``A speedboat riding low in the water can evade [the radar],'' he said.

``The night also provides some cover.''

``We think that ultra-right-wing Cubans in the United States are stimulating this and breaking U.S. law,'' he said. ``To us, this constitutes an international criminal act. They are infringing on our territorial waters.''

Polo said U.S. border authorities are the main culprits in failing to halt the speedboat traffic.

But a foreign official who visits Cuba often said he believes corruption is reaching lower level military and border guard officers, who have little legal access to the U.S. dollars increasingly necessary for survival in Cuba. He said the officials may be looking the other way at the smuggling.

``What's going is that we've got a growing cottage industry here, running people north. So rather than sitting back, unable to pursue them with boats that don't have enough fuel or spare parts, then maybe [the Cuban officials] think, `Maybe we can catch some dollars here,' '' he said.

In a sign of the importance Castro has put on the matter, Jan. 5 he devoted part of a five-hour speech on crime to smuggling. He said authorities had broken up 90 different smuggling attempts between January and November 1998, involving 660 people.

``They come from U.S. territory in fast boats at speeds of 70 to 80 kilometers an hour [44 to 50 mph]. They make arrangements through a visitor of Cuban ancestry, of whom there are tens of thousands per year,'' Castro said.

``It's not difficult to establish a point and a designated hour along the thousands of kilometers of our coastline to pick up family members of those residing in the United States or others interested in emigrating.''

A clearly irritated Castro said U.S. residents pay an average of $8,000 to speedboat operators for each Cuban who is taken to U.S. shores.

``Sometimes they take 12, 15, 20 and even more [people] on these fast, small boats,'' he said. ``Recently, 14 people drowned, including some children, when an overfilled boat sank near the coast of Florida.''

Cubans permitted to stay

Smuggling is fostered, Castro said, by favorable treatment given to Cuban refugees. Unlike immigrants of other nationalities, Cubans who actually set foot on U.S. soil are permitted to remain in the United States rather than being deported.

``This has turned into real encouragement for illegal departures and the smuggling of people,'' Castro said.

Only those Cubans who are intercepted on the high seas are returned to the island. About 1,500 Cubans found in the Florida Straits have been repatriated by the U.S. Coast Guard since 1995.

Castro said it would be logical for Cuba to deport captured smugglers to the United States to stand trial.

``We need the room in our jails for drug traffickers and those who commit other serious crimes,'' he said.

But U.S. courts show too much leniency, Castro said, even freeing those who hijack Cuban vessels and aircraft to flee the island, so Cuba will keep and try smugglers, running the risk that they may be portrayed abroad as political prisoners.

Legal Cuban immigration to the United States has flourished since the signing of an immigration accord in 1994. Last year, about 23,000 Cubans immigrated to the United States through legal means.

Discontent over deteriorating living conditions and a never-ending economic crisis makes thousands of Cubans eager to leave the island any way they can.

Alleviating the emigration pressure is the stream of U.S. dollars flowing to Cubans from relatives abroad. Since 1994, remittances have soared to an estimated $750 million a year, becoming a pillar of the Cuban economy.

In a change from the past, Cubans are increasingly seen in the hard-currency stores and restaurants once filled only with foreign tourists carrying U.S. dollars.

Herald staff writers Frank Davies and Juan O. Tamayo contributed to this report.