By Michael Voss
BBC News, Havana
Raul Castro officially became president in February 2008
The number of political prisoners in Cuba has fallen in the past six months, according to a new report by the island's main human rights group.
This continues the trend which began after Raul Castro took over the leadership of the communist island from his brother, Fidel, two years ago.
But the report also says that the authorities are continuing to take a tough line against dissidents.
It says that any change in the human rights situation remains "unlikely".
There are an estimated 219 political prisoners currently held in Cuban jails, 15 fewer than in January this year.
But according to the Cuban Commission for Human Rights and National Reconciliation (CCHRNR) this does not represent a fundamental change in the treatment of dissidents under Raul Castro.
Instead, the latest half yearly report by this illegal but tolerated organisation points to a change in tactics, with a marked increase in what it calls arbitrary systematic detentions.
Instead of high profile arrests and imprisonment, opponents are picked up by police, often prior to planned meetings or rallies.
They are then released without charge, usually within 24 hours.
Raul Castro has introduced some political and economic reforms
The head of the commission, Elizardo Sanchez, says in the report that any improvements in human rights remain "unlikely" at least in the short-term.
There has been a slow but steady decline in the number of prisoners over the past two years. But most of those released have served their time or were freed on health grounds.
The Cuban authorities deny that there are any political prisoners. Instead, they are referred to as mercenaries, paid by the United States to undermine the revolution.
Since Raul Castro took over this one party state from his ailing brother Fidel, Cuba has signed the UN Human Rights Conventions.
President Castro has also lifted restrictions on owning mobile phones and computers as well some economic reforms. But political change to this one party state is not on the agenda.