At least 35 Cuban political prisoners have been released in the last two days, dissident leaders said Thursday, as Cuba moves towards normalizing ties with the United States.

Washington and Havana announced a historic bilateral rapprochement in mid-December in which Cuba agreed to free 53 political prisoners as part of a deal to end a five-decade standoff with the United States.

Cuba has freed some of the 53 political prisoners identified on a U.S. list as it moves towards normalizing ties with the United States, an American official said Tuesday.

"They have already released some of the prisoners," State Department spokeswoman Jen Psaki told reporters.

Cuba on Monday convened municipal elections, in which the ruling party allegedly ensures that no opposition candidates even run for office.

The voting will be April 19, with runoffs a week later where needed, said the Council of State, the highest body in the government.

A Cuban crackdown on dissident activists caused a new rift with the United States on Wednesday, the first diplomatic scuffle since this month's historic announcement of a renewal in ties.

Authorities arrested 51 dissidents Tuesday to stop them from attending an open mic session convened for Cubans to speak out about their future, said Elizardo Sanchez, the head of the officially banned Cuban Human Rights and National Reconciliation Committee.

Cuba's arrest of several dissident activists caused a new rift Wednesday with the United States, the first diplomatic scuffle since this month's historic announcement of a renewal in ties.

Washington condemned Havana's "lack of respect" for human rights after the communist authorities on Tuesday arrested leading figures expected at an open mic session convened for Cubans to speak out about their future.

The United States expressed concern Wednesday over the plight of several dissidents detained by Cuba, just two weeks after Washington's historic move to normalize relations with Havana.

"We are deeply concerned about the latest reports of detentions and arrests by Cuban authorities of peaceful civil society members and activists," the U.S. State Department said in a statement.

Two Tunisian and three Yemeni detainees were transferred from the U.S.-run prison at Guantanamo Bay to Kazakhstan on Tuesday, the Pentagon said.

The move is part of President Barack Obama's stepped up effort to close the controversial military jail, which was set up to detain terror suspects after the September 11, 2001 attacks.

Experimental Cuban performance artist Tania Bruguera has asked her compatriots to share their dreams for the island's future at a "participatory performance" Tuesday likely to ruffle the communist government.

Venezuelan President Nicolas Maduro, a frequent critic of the United States, congratulated the Castro brothers Friday on Cuba's rapprochement with Washington, but warned that the embargo on the island would remain for a long time.

This month's historic announcement that the United States and Cuba were restoring diplomatic relations after half a century of hostility undercuts the stridently anti-American stance Maduro has adopted as his country slides into a deepening economic crisis.

Cuban expatriates in America, including many who risked their lives to escape the communist island, are torn about whether to return after Havana and Washington formally reestablish ties next year.