By Fergal Parkinson BBC correspondent in Miami

The Cuban Government has reacted angrily to rumours circulating in the United States and in Cuba that thousands of people are planning to leave the island, bound for Florida.

The rumoured plan is similar to that in 1994, when 30,000 Cubans took to the sea in flimsy rafts and other makeshift boats heading for the southern tip of Florida.

The exodus is said to be planned to coincide with US Independence Day.

Although nobody is sure how the rumour started, or indeed if it is true, both countries are taking no chances.

Thousands attempt the illegal journey each year

The US Coastguard has increased patrols along the 140-kilometre (87-mile) stretch of sea separating the two countries, while the Cuban authorities say the rumours are just vulgar provocations by the "terrorist mafia" - a favourite term for the anti-Castro exile community in Miami.

Despite the fact that 20,000 Cubans are allowed to enter the US legally every year, thousands more attempt the journey illegally aboard smugglers' boats.

Since 1995, Cubans picked up at sea by the US Coastguard have been sent back to their home country, while those that make it to US soil are allowed to stay.

"Migrants rescued at sea will be expeditiously repatriated back to Cuba according to current procedures," the US Coastguard said in a statement.

The Castro government in Havana blames this law for encouraging its inhabitants to make the dangerous crossing that takes the lives of dozens of Cubans every year.