The plane was hijacked by six men armed with knives

Six men, some armed with knives, are said to have taken control of the plane on Wednesday evening, as it headed to Havana from Cuba's Isle of Youth.

The hijackers broke down the cockpit door and restrained crew members with tape and rope, ordering the pilots to fly to Florida's Key West, the American authorities said on Thursday.

The plane's crew and passengers - including five children and an Italian tourist - are now being questioned by the US authorities at a federal detention centre near Miami.

The six alleged hijackers are being held at a county jail in Florida, and may be charged with air piracy.

Meanwhile Cuba has demanded the return of the hijacked plane, together with the passengers and crew.

On Thursday the government in Havana labelled the hijacking "an act of terrorism", and said it wanted the American authorities to provide further details about the incident.

History of defection

The motive for the hijacking is still unclear, according to an FBI spokeswoman.

The DC-3 plane landed safely at Key West's airport

But Cuban planes have been hijacked and flown to America before, by people wanting to seek asylum in the US.

Cubans are generally allowed to stay if they reach US soil.

Florida Coast Guard Joseph Nimmich said the motive for the hijack was likely to be defection.

But in most other such cases, the hijackers have been the pilots themselves. This was the first case in several years of a pilot being forced to divert his plane by armed attackers.

'Political problems'

US Air Force fighter jets intercepted the DC-3 plane, run by Cuban state airline Aerotaxi, shortly before it reached Florida late on Wednesday evening.

The US jets then escorted the plane to Key West's airport, where the suspects surrendered without incident.

The first indication of trouble came only half an hour into the flight, according to a Cuban statement.

The pilot radioed to say he had "political problems"on board and was heading north to Miami.

Minutes later he said the plane was being hijacked by "armed people" and requested the shortest flight plan possible for Key West, because he was short on fuel, the Cuban statement said.