By Daniel Wallis and Nelson Acosta
HAVANA (Reuters) - Cuba freed two more detainees, dissidents said on Thursday, as Havana began to release 53 people the United States considers political prisoners, as part of an agreement between the two nations aimed at ending decades of hostility.
Five detainees have been liberated over the past 24 hours, political opposition groups on the communist-led island said, including three others on Wednesday - all members of the dissident Patriotic Union of Cuba (UNPACU).
The commitment by Havana to free the prisoners was a major part of an historic deal announced last month, under which the two governments agreed to renew diplomatic relations after more than 50 years.
The latest two detainees to be freed were Ernesto Riveri Gascon and Lazaro Romero Hurtado, UNPACU said.
Like the three released on Wednesday, the pair had been accused of relatively minor offenses.
Romero was arrested in 2012 and sentenced to four years behind bars on charges including making a public disturbance and threats, apparently during a confrontation with police. Riveri was given two years on the same charges.
Cuba's government does not comment on police actions involving detentions, and has said nothing about this week's releases.
Elizardo Sanchez, president of the dissident Cuban Commission for Human Rights and National Reconciliation, which monitors such detentions, said more releases were expected on Thursday and over the coming days.
"That could indicate the start of the process ... under which around 50 Cuban political prisoners would be released from custody," Sanchez said in a statement.
Jose Daniel Ferrer, executive secretary of UNPACU, said 38 members of his organization remained in custody.
All five of those freed appear on an informal list drawn up by dissidents, but it is not known if they were on the official list of 53.
Details about the political prisoners who will be freed have been withheld by both governments, providing ammunition for Republican congressional opponents and other hardline critics of the policy shift.
One congressional aide, speaking on condition of anonymity, told Reuters Wednesday that Cuba was resisting the release of some prisoners on the list, but a White House official denied that, saying the U.S. government fully expected all 53 to be liberated.
Cuban and U.S. officials are due to hold talks in Havana later this month on migration and the normalization of diplomatic relations.
(Editing by Bernadette Baum)