Guillermo Farinas, a leading Cuban dissident and winner of the European parliament's top human rights prize, was arrested and for the first time beaten in detention, said his mother and activists.
Farinas, who won the Sakharov rights prize in 2010 after going on a 135-day hunger strike to press for the release of political prisoners, had gone to a hospital in Santa Clara to visit another dissident on a hunger strike, said his mother Alicia Hernandez from Santa Clara.
"According to what I was told by someone who was with him, he was on his way in and (state agents) told him no, and there was some kind of melee and they arrested him," Hernandez told AFP.
One of the agents "held him kept him in place, while another beat him. They have him in the police unit," she added, noting: "They had never before physically abused him."
Elizardo Sanchez, head of the Cuban Committee for Human Rights and National Reconciliation, said Farinas, who had gone to visit dissident Alcides Rivera, was still being detained at 0001 GMT Wednesday.
Farinas, 49, also a dissident journalist who has pressed for a free press and against Internet censorship in Cuba, was also detained in September when he tried to take part in a street protest in Santa Clara, a city east of Havana.
He has launched more than two dozen long hunger strikes in over 15 years, in an ongoing, bold confrontation with the Americas' only one-party Communist government. Farinas, who has said he is willing to die for the cause of Cuba's political prisoners and opposing censorship, has been mentioned as a possible Nobel peace prize candidate.
Cuban dissident Orlando Zapata died in Cuba on February 23, 2010 on the 85th day of his hunger strike.
Zapata's death at the age of 42 drew global attention to the plight of political dissidents, and the human rights situation, in Cuba.
Farinas was awarded the Sakharov prize last year following the February death of fellow dissident Zapata.
He ended the protest when President Raul Castro authorized the release of 52 political prisoners -- out of a group of 75 arrested in 2003 -- on the heels of talks with senior Roman Catholic Church clerics in Havana.
Farinas was the third Cuban to receive the Sakharov prize, after dissident activist Oswaldo Paya in 2002 and the 2005 award to the Ladies in White, a group of women whose dissident husbands are jailed.
A former soldier and supporter of Fidel Castro's revolution, Farinas distanced himself from the regime in 1989 when he opposed the execution of general Arnaldo Ochoa, who was accused of drug trafficking.
The Cuban government, which skirts the issue in its official media outlets, still denies holding any political prisoners; it says they are mercenaries in the pay of the United States.