They have accused Castro of committing acts of ''false imprisonment, murder, torture and the violation of human rights'' during his 42 years in power.

The Cuban exiles handed the lawsuit to an investigating judge at the Brussels criminal court.

The primary plaintiff in the Cuban case is Jose Basulto, president of the Miami-based group Hermanos Al Rescate ('Brothers to the Rescue'), which conducts aerial search missions for Cubans fleeing the Caribbean island and helps them resettle in the United States.

The non-profit organisation - founded in May 1991 by a group of pilots moved by the story of a 15-year-old boy who died of severe dehydration while fleeing Cuba by raft - has conducted more than 2,400 such missions since then.

On Feb 24, 1996, Cuban Air Force jets shot down two of the group's planes, killing four people. ''Fidel Castro chose to send his MIGs (Soviet-made fighter jets) after us - on one given mission of about 2,000 to that date - and in the same place we have searched before,'' he told reporters Thursday.

''The act was a premeditated ambush of our planes,'' he said.

Basulto, who was travelling in a third plane on that mission over the Florida Straits and escaped unharmed, said the Cuban president had ordered the deadly attacks knowing full well it posed no military threat to Cuba.

''We have spent four years collecting evidence that identifies Fidel Castro as being responsible for their deaths, and now have the opportunity to test that evidence (in Belgium) through a respected international legal process,'' said Basulto.

He said there were over 1,500 pages documenting an orchestrated campaign against Hermanos Al Rescate that culminated in the 1996 attacks. One Cuban has been convicted in a U.S. court in connection with the shoot-down.

He was found guilty of conspiracy to commit murder, though the case is under appeal. In August, more than 100,000 people petitioned the United States to indict Castro and his brother, Gen. Raul Castro Ruz, the former head of the Cuban secret services, on murder charges.

''We expect to find justice in Europe as in America,'' said Baulto.

The controversial Belgian law under which the Cuban exiles are seeking to try Castro and members of his government is at the centre of an attempt to try Israel's prime minister, Ariel Sharon, over a 1982 massacre of Palestinians in Israeli-occupied Lebanon.

An appeals court is debating whether Sharon can be prosecuted in Belgium. A suit also has been filed against former Chadian leader Hissene Habre (known as the 'African Pinochet'), who is believed to be responsible for some 40,000 executions and the torture of 200,000 people during his eight-year rule, which ended when he fled to Senegal in 1990.

''Fidel Castro himself boasted at the time of the shoot down as to how he was responsible - personally responsible. We have videotapes of that admission on CBS News and CNN,'' said Larry Klayman, chief counsel for Bastrulo and 10 other plaintiffs.

''But this (writ) is not only about Brothers to the Rescue. You are going to hear from other victims of Fidel Castro,'' he said. ''And we thank Belgium for having a law that can bring these kind of people to justice. This case is more compelling than any such case ever before brought in Belgium. This is not an isolated instance, like the case against Ariel Sharon. This is 42 years of murder and persecution and torture... Nearly 100,000 people have been killed,'' said Klayman.

He is chair of Justice Watch, the Washington-based non-profit organisation that is representing the Cuban exiles. The writ, delivered to the same Belgian magistrate who handled the complaint against Sharon, is available in French on: http://www.judicialwatch.org/cases/castrocomplaint.html

In addition to testimony by the plaintiffs, it cites numerous reports by international rights watchdogs such as Amnesty International and Human Rights Watch.

''Cuba routinely denies human rights abuses, fails to investigate or punish those who commit them, and retaliates against those who denounce them, particularly prisoners,'' said HRW.

Eugenio de Sosa Chabau, a former newspaper editor, who spent 20 years in prison after a Cuban court found he had committed ''dissident political activities'' for speaking out against Castro, is another plaintiff in the complaint issued Thursday.

The 85-year-old Cuban-American, who lives in Florida, travelled to Brussels to personally deliver the complaint.

De Sosa told reporters that during his imprisonment from 1960 to 1980, prison guards had broken half the bones in his body, stuck him with bayonets and delivered electric shocks to his groin.

''I was continuously tortured,'' he said.

Marcelino Feal, another party to the complaint and a political prisoner who served a 17-year sentence in Cuba, said guards had beaten him so severely that he lost sight in his left eye.

Two others named in the writ are Cubans resident in Brussels. Attorney Paul Sher, who is based in Belgium, and with Klayman, is representing the plaintiffs, said he expected many other Cubans living in Europe would be coming forward to give evidence.

Still, it is not certain the case will be pursued. First, the investigating judge will have to determine whether the case against the 75-year-old Communist leader is admissible.

Furthermore, Belgian authorities are already investigating almost a dozen complaints involving current and former leaders, and only three federal policemen are assigned to the crimes- against-humanity unit.

Those under investigation include Iraqi President Saddam Hussein; former Iranian President Hashemi Rafsanjani; former dictator of Chad, Habre; as well as former Moroccan interior minister, Driss Basri.

Charges also have been filed in Brussels against Guatemalan generals and elements of Cambodia's Khmer Rouge regime.

In April, in the first prosecution under the law, two Roman Catholic nuns, along with two men, from Rwanda were convicted of aiding and abetting the murder of Tutsis as part of the genocide that swept the Central African nation in 1994.

But Belgian Foreign Minister Louis Michel has made clear the government wants to amend the law, which blurs the line between the country's federal and judicial powers, to prevent future prosecutions of sitting heads of state or government. The Sharon case embarrassed the government when it caused the Israeli prime minister not to visit European Union headquarters in Brussels.

Although Castro is not slated for a visit to Europe, Belgium, which currently holds the rotating EU presidency, recently headed a mission to Havana to improve diplomatic relations, which had cooled following the EU's criticism last year of the Cuban human rights record before the United Nations in Geneva.