Six dissidents were freed Thursday as part of a deal made between Cuba and the US to release 53 political prisoners, but a key Cuban exile and rights activist group continues to question why the deal is shrouded in secrecy.

Since Cuba agreed with the Obama Administration on December 17th to free 53 detainees, considered to be high priority political prisoners by Washington,  neither Cuba nor the United States has publicly identified anyone on the list. In fact, neither government spoke publicly about the releases Thursday.

On Wednesday, the head of Cuba's Human Rights and Reconciliation Commission, Elizardo Sanchez, told The Associated Press that the three released prisoners were 19-year-old twins Diango Vargas Martin and Bianko Vargas Martin and Enrique Figuerola Miranda. On Thursday morning, he said that prisoners Ernesto Riveri Gascon, Lazaro Romero Hurtado and David Piloto had also been released.

The freed twin brothers were members of the Patriotic Union of Cuba, a small dissident anti-Castro group. 

While the release is a good sign that the Cuban government will follow through on its deal with the U.S., activists remain frustrated by the lack of transparency.

The Foundation for Human Rights in Cuba, a Miami-based non-profit dedicated to supporting anti-Castro activists and their families, says the fact that the 53 political prisoners have not been publicly identified is an example of an administration that is too trusting of the Castro regime.

"We would like to know the names, because obviously these people are going to need help when they are released, and we want to make sure that they are released," said Francisco "Pepe" Hernandez, co-founder and president of the FHRC told Fox News Latino. "Everyone is mute, why is that?"

The frustration led the FHRC to release their own list of 57 political prisoners calling on the White House and the Vatican to demand their immediate and unconditional release. The majority of the listed prisoners have been arrested within the last two years on what they claim are bogus charges of assault and public disorder. They were sentenced anywhere from a year to life in prison. All six men released Thursday were on the FHRC list. 

Hernandez's organization sends humanitarian aid to the families of political prisoners every month and aids the opposition there. He is demanding the names of the 53 political prisoners to ensure that the Castro regime is held accountable if they renege on their promise.

One of the concerns is that Castro regime could release political prisoners and then exile them for life from the island, keeping the prisoners from ever seeing their families. In the past, the regime has freed political prisoners only to exile them in an effort to stop them from promoting freedom on the island. Hernandez also thinks the Castro regime could choose to instead release common criminals, instead of actual political prisoners, because they are afraid of re-energizing the opposition on the island.

"It is something that is very disconcerting for those of us trying to help," Hernandez said. "To tell you the truth, I don’t know, after all these years, how this government can be so naïve with the Castros."

Sen. Marco Rubio, R-Fla., a Cuban-American, echoed Hernandez's sentiments demanding more clarity on the identities of the 53 Cuban political prisoners in a Jan. 6 letter to President Obama writing “the least your administration can do now is hold the regime accountable for fully freeing these 53 political prisoners as well as those who have been detained in recent weeks.”