As Cuba on Thursday marked the 40th anniversary of an alleged U.S.-backed terrorist attack on a Cuban passenger plane, relatives of the victims said they were still awaiting justice.

"We demand justice and an end to the impunity that has marked this crime over the past 40 years," Thalia Gattorno Espinosa, whose grandfather was the copilot, said at a ceremony held at Havana's Revolution Plaza.

The bombing of Cubana de Aviacion flight 455 on Oct. 6, 1976 killed all 73 people on board after it exploded in midair and went down off the coast of Barbados.

The attack was found to have been organized by anti-Castro Cuban exiles -- Luis Posada Carriles, a known CIA operative, and Orlando Bosch -- and carried out with the help of two Venezuelans.

Family members, officials and others held a vigil at Havana's cemetery on Wednesday night, carrying photos of the 68 passengers and five crew members.

Among the dead were all the 24 members of the national Cuban fencing team that had just won all the gold medals at the Central American and Caribbean fencing tournament.

Five years ago, Cuban President Raul Castro decreed Oct. 6 to be the Day of Victims of State Terrorism.

"We have seen with pain how this injustice has lasted for 40 years, and we will continue our struggle to bring to justice the terrorists that perpetrated the attack," said Jorge de la Nuez, whose father died in the explosion.

Cuba accused Washington of having a hand in the attack. CIA documents declassified in 2005 showed the agency knew as early as June 1976 about the plot by Cuban exile terrorist groups to bomb a Cubana airliner.

"We hope the next U.S. administration doesn't forget about Cuba's victims of terrorism and finally agrees to cooperate with our government in this matter. Posada Carriles could die tomorrow, but that won't eliminate the threat of terrorism against our country," said De la Nuez.

Posada Carriles and Bosch had both worked as CIA agents in South America, taking part in numerous plots against Cuban revolutionary leader Fidel Castro and terrorist attacks on Cuban embassies and assets abroad.

They and their two Venezuelan accomplices stood trial in Venezuela for the plane attack and were imprisoned. Posada escaped in September 1985 and reportedly entered the United States. Bosch was released in 1987 and also returned to the United States, where he died in 2011.

Source : XINHUA