Obama and Raul Castro in historic handshake

US President Barack Obama and Cuba’s Raul Castro have shaken hands at the Summit of the Americas, a new milestone in efforts to shed decades of animosity between the two countries.

The two leaders – who briefly shook hands once before, at Nelson Mandela’s memorial service in Johannesburg in 2013 – exchanged a few words on Friday as Ban Ki-moon, UN secretary-general, and regional leaders looked on, before taking their seats at a Panama City convention centre.

The sight of Obama and Castro in the same room instantly became a potent symbol of their bid to renew diplomatic ties that were severed in 1961.

It was the first time that a Cuban leader attended the summit in its 21-year history.

A US official characterised the Obama-Castro greeting as an “informal interaction”, adding that “there was not a substantive conversation between the two leaders.”

A widely anticipated broader conversation – the first between US and Cuban leaders since ties broke in 1961 – is expected on Saturday.

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“The presence here today of President Raul Castro of Cuba embodies a longing expressed by many in the region,” Ban said.

All the regional leaders then headed to a private dinner.

Ben Rhodes, a senior Obama aide, said the extent of Saturday’s Obama-Castro meeting had yet to be decided, but that they will “take stock” of the negotiations to reopen embassies and discuss lingering “differences”.

Rhodes said Obama and Castro had already discussed the ongoing negotiations and the summit by telephone on Wednesday – their second phone call since December, when they announced that the US and Cuba would move to normalise relations.

Al Jazeera’s Lucia Newman, reporting from Panama City, said the summit opened amid “loud banging of pots and pans from buildings surrounding the area”, a familiar sign of protest against the Venezuelan leader, Nicolas Maduro, used often by opponents of his leftist government.

“Maduro and host President Juan Carlos Varela pretended not to hear as he greeted Maduro, although it was impossible not to notice,” she said. 

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“The Papal Nuncio [Vatican Ambassador] Pietro Parolin read out a letter from Pope Francis to ceremonially open the proceedings.

“He said that he hoped that a sincere dialogue would overcome differences in order to find common points of view that could help overcome the region’s problems.”

For his part, Ecuador President Rafael Correa issued a stern warning to his US counterparts about Venezuela and Cuba. “We will not accept any interference in our internal affairs,” he said.

Underscoring his increasing engagement with Latin America, Obama will also perhaps meet Colombian President Juan Manuel Santos and Brazilian President Dilma Rousseff, who cancelled a US trip in 2013 over revelations of US spying against her.

But in a move that could irritate Cuba, Obama held a closed-door discussion before the summit with dissident lawyer Laritza Diversent and political activist Manuel Cuesta Moura, along with a dozen other activists from the Americas.

While declaring that the days of US meddling in the region were over, Obama promised civil society representatives that “the United States will stand up alongside you every step of the way.”

Turning to Cuba, Obama said that even as “a new chapter” in relations was launched, “we’ll have our differences, government to government, with Cuba on many issues.”

For his part, Castro held talks with Tom Donohue, president of the US chamber of commerce, putting together the leader of the only communist regime in the Americas with a major figure of capitalism.

John Kerry and Bruno Rodriguez, respectively the US and Cuban foreign ministers, held late on Thursday the highest level talks since 1958, which both sides hailed as “constructive”.

But Rhodes said there was no decision yet on one of the key obstacles in diplomatic negotiations, Cuba’s presence on the US blacklist of state sponsors of terror.