Amnesty International has accused the Cuban authorities of holding 71 prisoners of conscience, often in brutal conditions.
Wives of dissidents held in Cuba staged a demonstration last month
Cuba continues to imprison people who simply disagree with the state, the rights group has said in a new report.
Those who meet US officials or talk with exiles in the US can face jail terms of up to 28 years, Amnesty says.
Two years ago, Cuba saw the harshest clamp down on human rights since the revolution in 1959.
Ban on clothes
Amnesty - which has been denied access to Cuba since 1988 - said four political detainees have suffered abuse during the last year.
The group said prisoner of conscience, Juan Carlos Herrera Acosta, was beaten on his throat by prison guards, until he lost consciousness.
Nine dissidents were locked in cells measuring 1m by 2m, without a break, for between two and four months. In some cases, the detainees were forbidden to wear clothes.
Cuba has rejected calls from Western governments to free political prisoners.
However, over the last year, the authorities have released 19 political detainees, of which 14 were freed on health grounds.
Amnesty has once again criticised the US embargo on Cuba, which it says gives Fidel Castro's regime an excuse to clamp down on dissidents.