By Patricia Zengerle and Lesley Wroughton
WASHINGTON (Reuters) - Political detentions have declined in Cuba since the Dec. 17 U.S.-Cuban rapprochement but it is unclear if this is a trend, a U.S. human rights official told a congressional hearing on Tuesday.
"The nature of the Cuban regime has not changed and we have not claimed so," Assistant Secretary of State Tom Malinowski told U.S. lawmakers' first hearing on Cuba since President Barack Obama and Cuban President Raul Castro said they would seek to normalize relations.
Malinowski said roughly 140 political opponents had been temporarily detained by the Havana government in January.
"From December to January we have actually seen a significant decrease but I don't want to say that one month represents a trend," he told a Senate subcommittee. "Even a single one of these detentions is too many. We're going to be watching this very carefully."
The Cuban Commission on Human Rights and National Reconciliation said on Monday Cuban police detained 178 opponents of the Castro regime in January, the lowest monthly total in more than four years.
The lead U.S. negotiator in the Cuba-U.S. talks, Roberta Jacobson, said a second round of talks to restore diplomatic relations would likely take place in February.
Some lawmakers offered blistering criticism of the policy shift. Democratic Senator Robert Menendez said Obama had "compromised bedrock principles" in exchange for little from Havana and pledged to oppose any efforts to ease the 50-year-long Cuban embargo.
"It was a bad deal," he said.
Jacobson reassured lawmakers that the United States would not bow to Cuban demands to drop support for Cuban dissidents. While in Havana last month, Jacobson said improving human rights and democracy in Cuba was a cornerstone of the new policy.
"Can't imagine we will go to next stage with an agreement not to see democracy activists," Jacobson said.
The hearing was chaired by Republican Senator Marco Rubio, a Cuban-American who opposes normalizing relations with Cuba and is a likely 2016 presidential candidate. He argued that restoring ties would not improve the island's human rights record.
Congress is deeply divided over the shift in Cuba policy, with supporters and opponents divided among Democrats and Republicans.
Backers at the hearing said the change would improve U.S. relations with other countries, especially in Latin America. Senator Barbara Boxer, the top Democrat on the subcommittee, brought statements from 46 foreign governments supporting Obama's policy.
(Reporting by Lesley Wroughton and Patricia Zengerle; Editing by Bill Trott and Doina Chiacu)