By CURT ANDERSON
Associated Press

MIAMI -- A prominent Cuban exile facing federal weapons charges allegedly planned and launched a commando raid against Fidel Castro's government in 2001 and maintained an arsenal in the Bahamas for future attacks, U.S. prosecutors said in court documents. A lawyer for the man denied the accusations.

Santiago Alvarez allegedly helped plan and pay for an April 2001 "armed incursion'' that was intended "to commit acts of violence against the government of Cuba,'' but the plot failed when the commandos were arrested and imprisoned in Cuba, according to the documents filed over the past two weeks in U.S. District Court.

After Alvarez's arrest last year, an informant told the FBI that Alvarez had a large cache of weapons on Guinchos Cay, an island in the Bahamas about 12 miles from Cuba. In August 2005, the Coast Guard discovered numerous guns, grenades, grenade launchers and about five pounds of powerful C-4 plastic explosives, the documents said.

Alvarez and co-defendant Osvaldo Mitat ``have been involved in planning and staging insurgent paramilitary operations against Cuba,'' prosecutors said. ``The weapons seized in this case have been acquired and stored by the defendants in support of these past, present and future efforts.''

Cuba announced in April 2001 that it arrested three heavily armed men linked to Miami exile groups for plotting acts of sabotage against the Castro government. It was not clear Friday whether they remain in custody or whether they were the same commandos referred to in the new court documents.

Officials at the Cuban Government Interests Section, which represents Cuba in Washington, did not return a telephone call seeking comment.

Alvarez and Mitat, both 64, are scheduled to stand trial May 8 in federal court in Fort Lauderdale on weapons charges.

The case stems from the discovery of other stashes of military hardware at a Broward County apartment complex owned by Alvarez and in a large cooler being transported to Miami from the apartments.

Both have pleaded not guilty and are being held without bail.

Although both men are avowed opponents of Castro's communist government, their attorneys said Friday that the government's new allegations about paramilitary activities are based mainly on an informant's claims and that there is little supporting evidence. They also say the informant is a double agent who worked for Cuba and the FBI.

``None of that is provable,'' Alvarez attorney Kendall Coffey said. ``He's not charged with any of that.''

Coffey said defense lawyers will attempt to have the evidence excluded from the trial. In their own court motion, they called the government's plan to introduce this evidence ``an outrageously offensive and unacceptable display of government stealth and surprise tactics'' that is not relevant to the case.

Assistant U.S. Attorney Randy Hummel, however, cited documents found during a search of the Miami-based Caribe Foundation, described as ``a center for Alvarez's militant anti-Castro activities.''

The evidence is relevant to the Broward County weapons case, Hummel said, because it shows that he and Mitat were actively procuring and storing weaponry in their ongoing struggle against Castro's government.

The court papers also disclosed more details about Alvarez's relationship with Luis Posada Carriles, another Cuban exile and former CIA operative who is wanted by Cuba and Venezuela for allegedly masterminding the 1976 bombing of a Cuban airliner. Posada, 78, has been in U.S. immigration custody in El Paso, Texas, since his arrest last year in Miami.

U.S. investigators found ``hundreds and hundreds of pages'' of documents showing Alvarez's support for Posada during Posada's trial and imprisonment for an alleged Castro assassination attempt in 2000 in Panama. Posada was later pardoned by Panama's president.

Alvarez, the documents said, ``was very active in raising funds'' for Posada's legal defense, later tried to get travel documents for Posada and was ``directly involved'' in smuggling Posada into the United States in March 2005. Alvarez was arrested not long after Posada was taken into custody.

Posada has been ordered by a federal judge to testify in the Alvarez case. A U.S. immigration judge has ruled that Posada cannot be deported to either Cuba or Venezuela because he might be tortured, but U.S. authorities so far have not found a third country willing to accept him and refuse to release him outright.