Tampa teenager Melissa González wanted to visit her ailing grandfather in Cuba. But her travel agency told her that the Cuban government had turned down her request for an entry permit, without explanation.

No doubt, said her father, Jorge Luis Gonzalez Tanquero, she was turned down because he is a former political prisoner who spent 7 ½ years in prison and has continued to blast the Cuban government since his arrival in South Florida in February.

Whatever the reason, Melissa now belongs to the little-known group of Cubans living abroad who are banned by Havana from visiting the island — anywhere from 77,000 to 300,000 — for reasons that range from illegal departures from Cuba to political activism.

But Cuban ruler Raúl Castro cast an indirect light on the issue last week when he declared that his government was working on the “reformulation” of migration regulations that have been in effect for a long time “unnecessarily.”

“We are taking this step as a contribution to the increase in the country’s links with the emigrant community,” Castro added, noting that in recent years Cubans have been leaving the island more for economic than for political reasons.

He gave no details but his comments were taken as hints that Cubans both abroad and on the island would be given more leeway to travel across borders, and that expatriates might even be allowed to invest in businesses or buy properties on the island.

Havana officials also have said that they expect a hefty increase in U.S. arrivals, perhaps from 300,000 in 2010 to 400,000 this year, as a result of President Barack Obama’s decision to let more Cuban Americans and non-Cuban U.S. residents visit the island.

“My impression is that the flow [of Cuban travelers in and out of the country] will soon be as regular and normal as any other part of Latin America,” said Max Lesnick, a Cuban-born Miami radio commentator who favors increased travel to the island.

Many of those banned from returning by Havana are Cubans who left illegally aboard flimsy homemade rafts, such as the 35,000 who took to the seas during the so-called “Balsero Crisis” of 1994.

Under a 1995 U.S.-Cuba migration pact designed to discourage Cubans from trying the risky raft escapes, Washington adopted the “wet foot-dry foot policy,” in which those intercepted at sea are returned to the island while those who reach U.S. land can stay.

Knowledgeable U.S. officials say Cuba, on its own and not as part of the 1995 agreement, decided to provide its own disincentive to the risky rafter voyages by forbidding the return of anyone who left the island illegally

That includes rafters as well as what Havana calls “defectors” — those who left legally on official trips, such as sports teams or trade missions, and stayed abroad. It does not include those who left legally on non-official trips, such as family visits.

The 77,000 estimate is a back-of-the-envelope addition of the 35,000 rafters in 1994 plus an estimate of those who left the island illegally since 1995 and other “undesirables,” said Pedro González Munné, a Cuban-born Miami travel consultant.

Nearly 14,000 rafters reached U.S. shores from 2005 to 2010 alone, according to U.S. government figures gathered by El Nuevo Herald. Thousands of others left Cuba illegally for Mexico and then made their way by land to the U.S. border.

The 300,000 estimate has been mentioned by Castro government officials, said one senior Cuba travel industry officials in Miami who asked for anonymity because of the political sensitivity of the issue.

An estimated one million island-born Cubans live abroad, most of them in the United States. Spain and Mexico are home to the second- and third-largest communities of Cuban expatriates.

Cuba enforces the ban on returns strictly and only rarely allows rafters to visit, usually to reunite with sick relatives, according to travel industry officials and employees interviewed by El Nuevo Herald.

The Cuban consulate in Washington, which must pre-approve all Cuban-American travelers, rejects about 20 of the 200 applications for permission to visit that her agency sends in monthly, according to one travel industry employee.

Migration officials in Cuba reject another one or two Cuban Americans per month after they review the passenger manifests her company sends them before departure, one official noted. The rejection reads, “Do not board for illegal exit,” she added. Another one or two per month are turned back at Cuban airports.

But other Cubans in Miami acknowledge that some daring rafters can travel to the island by providing fraudulent or misleading information on their applications to the Cuban consulate in Washington.

Andres told El Nuevo Herald that he left on a raft in 2005 and returned last year after “never mentioning the word raft.” Yolanda said she left during the 1994 Balsero Crisis and has returned five times. “No one ever asked how I left,” she said. Both asked that their last names not be used so they could continue traveling to Cuba.

In contrast, Melissa Gonzalez was 14 years old when she tried to buy her ticket to Havana in June to visit her 63-year-old grandfather Luis Gonzalez, sick and heartbroken after Melissa’s mother had suffered an incapacitating stroke in January. She died later.

Three weeks later, an employee of the Cuba travel agency where she had tried to buy a flight ticket told her that Cuban consuls in Washington had rejected her bid and asked her if she had had any idea why that was.

“They tortured me and now they are torturing her,” said her father, one of the 75 dissidents sentenced to lengthy prison terms in a 2003 crackdown. He was freed and sent to Spain earlier this year, and was swiftly issued a U.S. visa after his wife’s stroke.