The White House said today that Cuba has released all 53 prisoners it promised to free as part of a deal to normalize relations with the United States.

“We welcome this very positive development and are pleased that the Cuban government followed through on this commitment,” a senior Obama administration official said in a statement to reporters. “Our Interests Section in Havana was able to verify these releases.”

Both the United States and Cuba still won’t publicly identify the names of the prisoners.

The list is thought to have come from information provided by dissident activists in Cuba and human-rights groups, which helped compile names of people who had been jailed for having peacefully exercised freedom of expression and assembly.

Last week, after intense secrecy had surrounded the fate of the prisoners, the State Department announced that “some” of them were released. At that time, the State Department did not provide a specific number.

>>> Cuba Releases ‘Some’ of 53 Political Prisoners, US Finally Reveals

Their agreed upon release was part of Obama’s Dec. 17 announcement that he planned to restore “full diplomatic relations” with Cuba after five decades of hostile relations with the island.

The U.S. official says the administration will hold the Cuban government accountable if it continues to detain or harass other political opponents.

According to Reuters, which first broke the news of the freed prisoners, the White House will provide the names of the 53 prisoners to Congress and expects lawmakers to make them public.

Opponents of President Obama’s decision to restore diplomatic ties with Cuba expressed doubts that the island will deliver on its promises.

Sen. Marco Rubio, R-Fla., a Cuban-American and critic of Obama’s move, told “CBS This Morning” that “thousands” of political prisoners remain in Cuban jails.

“Certainly for those 53 prisoners it’s great news, but unfortunately we don’t know who they are,” Rubio said. “The list has been kept secret from the world. Beyond it, our understanding from the ones who have been released, is that many are at the end of their terms anyway and all have been warned that if they take up the cause of democracy they will be right back in jail.”