The five men are considered national heroes in Cuba
Some 130 celebrities from the arts, media and politics have signed an open letter calling for justice for five Cubans jailed in the US for spying.
The letter appeared in two national UK newspapers to mark on the 10th anniversary of the men's arrest.
Campaigners are urging US authorities to give visas to the wives of two of the men. They have not been allowed to visit the US for several years.
The men were convicted in a Miami court in 2001 on a range of charges.
These included lying about their identities, trying to obtain US military secrets and spying on Cuban exile groups.
Three were given life terms, the other two 19 and 15 years in jail.
A full-page advertisement in The Guardian and The Independent newspapers on Tuesday carries a large photograph of Adriana Perez, who has not been granted a visa to visit her husband, Gerardo Hernandez, for 10 years.
The letter details what it says was the unfair trial of the five men, the refusal by the US authorities to grant visas to Ms Perez and to another of the wives, Olga Salanueva, for several years, and restricting other family members to visits just once a year.
The signatories include 10 Nobel laureates, among them Archbishop Desmond Tutu of South Africa, German and Portuguese novelists Gunter Grass and Jose Saramago, and Guatemalan indigenous rights campaigner Rigoberta Menchu.
The men, Gerardo Hernandez, Ramon Labanino, Antonio Guerrero, Fernando Gonzalez and Rene Gonzalez, have appealed against their sentences, three times.
They say that by being tried in Miami, the centre of anti-Castro Cuban exiles, they were victims of bias.
US prosecutors insist the men were found guilty on hard evidence.
In June, an appeals court upheld the convictions but said the sentences of three of the men should be reconsidered.
The Cuban government says the men were not in Miami to spy on the US but to prevent anti-Castro exile groups from launching what it calls terrorist attacks on Cuba.
The men are considered national heroes in Cuba, where they figure prominently on billboards all over the country and are the subject of regular rallies and demonstrations.
Cuban exile groups say they were justly punished.