Cuban dissident Guillermo Farinas has launched a hunger strike, his 24th in 15 years, to ask the government to prosecute those "responsible" for the death of a fellow activist.

"I started the hunger strike today at noon (1600 GMT), demanding the government to bring the perpetrators of the murder of Juan Soto and stop beating dissidents," the 49-year-old Farinas told AFP via telephone from his home in Santa Clara, east of Havana.

The online journalist, who led a 135-day hunger strike last year to demand the release of political prisoners, said he would keep up his protest "until the ultimate consequences" and would only agree to negotiate with the government on "equal conditions."

Soto's supporters say he died last month after being taken to the Santa Clara hospital following his arrest in a park and subsequent beating. Cuban official media quoted Soto's doctor and his sister as saying that police brutality had nothing to do with his death.

Cuba authorities said Soto, who was in fragile health, had been arrested for a few hours by the police for a "public scandal," then freed "without incident."

Farinas, who was awarded the European Parliament's 2010 Sakharov prize, said Soto told him he had been beaten and that he had seen bruises on the lower back of Soto's corpse.

The Americas' only one-party communist regime has already detained Farinas several times this year.

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 government considers Farinas and the rest of the opposition as "mercenaries" on Washington's payroll.