Laying bare a half-century of tensions, US President Barack Obama and Cuban President Raul Castro prodded each other on Monday over human rights and the long-standing US economic embargo during an unprecedented joint news conference.

The exchanges underscored deep divisions that still exist between the two countries, despite rapidly improved relations.

Obama, standing in Havana's Palace of the Revolution on the second day of his historic visit to Cuba, repeatedly pushed Castro to take steps to address his country's human rights record.

"We continue ... to have some very serious differences, including on democracy and human rights," said Obama, who planned to meet with Cuban dissidents on Tuesday. Still, Obama heralded a "new day" in the US-Cuba relationship and said "part of normalizing relations means we discuss these differences directly".

Castro was blistering in his criticism of the US embargo, which he called "the most important obstacle" to his country's economic development. He also pressed Obama to return the US naval base at Guantanamo Bay, which is on the island of Cuba, to his government.

"There are profound differences between our countries that will not go away," Castro said.

When a US reporter asked about political prisoners in Cuba, he pushed back aggressively, saying that if the journalist could offer names of anyone improperly imprisoned, "they will be released before tonight ends".

"What political prisoners? Give me a name or names," Castro said.

Obama's and Castro's comments were broadcast live on Cuban state television.

At an outdoor cafe in Havana, about a dozen Cubans and tourists watched in silence. Ricardo Herrera, a 45-year-old street food vendor, said, "It's like a movie but based on real life."

After responding to a handful of questions, Castro ended the news conference, declaring, "I think this is enough."

Obama's visit to Cuba is a crowning moment in his and Raul Castro's bid to normalize bilateral relations. On Monday night, Castro honored his US guests with a state dinner at Havana's Palace of the Revolution.

(China Daily 03/23/2016 page12)