US President Barack Obama has described the historic thaw in US-Cuba relations as a “turning point”.
Mr Obama was addressing 34 other regional leaders, including Cuba’s President Raul Castro, at the Summit of the Americas in Panama.
The US president is due to meet Mr Castro on the sidelines of the summit.
It will be the first top-level negotiations between their countries in more than 50 years and their first formal meeting since the thaw began.
Addressing the same plenary in Panama City on the summit’s second day, Mr Castro called for the decades-long economic blockade on Cuba to be lifted.
He also described Mr Obama as an “honest man” after a lengthy speech largely taken up with the history of US-Cuba relations.
“When I talk about the revolution, the passion oozes out of me,” the Cuban leader said. “I have to ask President Obama for forgiveness. He is not responsible for the things which happened before his time.”
Earlier, Mr Obama told fellow leaders: “This shift in US policy represents a turning point for our entire region.
“The fact that President Castro and I are both sitting here today marks a historic occasion,” he said, while admitting there were still significant differences.
The US broke off diplomatic relations with Cuba in 1959 after Fidel Castro and his brother Raul led a revolution toppling US-backed President Fulgencio Batista. The Castros established a revolutionary socialist state with close ties to the Soviet Union.
At past Summits of the Americas, which bring together the leaders of North, Central and South America, the US has come in for criticism for its embargo against Cuba and its objection to Cuban participation.
This seventh summit is the first which Cuba is attending. Attempts to improve relations between the US and Cuba began in December when Mr Obama declared Washington’s approach “outdated”.
The US president is expected to raise the issue of political reform in Cuba when he meets Mr Castro. Human rights are also of concern to Washington.
Along with an end to the embargo, Havana wants removal from Washington’s list of state sponsors of terrorism, something Mr Obama has already signalled he is prepared to do.
Cuba’s presence on the list has been one of the main hurdles on the way to closer ties between the two countries as it hampers Cuba’s ability to conduct financial transactions.
The two leaders may still be able to find a path through their shared difficulties and discuss a date for reopening embassies in their respective capitals in the near future, says the BBC’s Will Grant in Panama City.
The smooth progress made between Cuba and the US stands in contrast to the bumpy ride that US-Venezuela relations have experienced over the past months.
The two countries have not exchanged ambassadors for more than six years. Tensions rose last month when the US imposed sanctions on a group of Venezuelan officials it accuses of human rights abuses.
As part of the sanctions, Mr Obama issued an executive order declaring Venezuela a threat to US national security.
President Maduro has collected more than 10 million signatures demanding its repeal and plans to present them to Mr Obama.
Mr Maduro sent out mixed messages on Friday, visiting a monument to victims of the 1989 US invasion of Panama but also saying that Venezuela was at the summit “in a constructive spirit, to make history through respect”.