Obama and Castro at the summit (Reuters)

US President Barack Obama and Cuban President Raul Castro today met on the sidelines of the Summit of the Americas in Panama, the first such meeting between the leaders of the two countries since 1959.

"[Obviously] there are still going to be deep and significant differences between our two governments," Mr Obama said, even as he welcomed "the spirit of openness and courtesy" Mr Castro had shown during their meeting.

"What we have both concluded is that we can disagree with a spirit of respect and civility," he said. "Over time, it is possible for us to turn the page and develop a new relationship between our two countries."

The president said the US will not ignore rights issues on the island.

"We will continue to try to lift up concerns around democracy and human rights," he said.

"[Some] of our immediate tasks include normalizing diplomatic relations and ultimately opening an embassy in Havana, and Cuba being able to open an embassy in Washington, D.C. so that our diplomats are able to interact on a more regular basis," the US president added.

Raul Castro, the brother of revolutionary leader Fidel Castro, said patience was needed but that Cuba was ready to talk about sensitive topics.

"We are willing to make progress in the way the president has described," he said.

During his address to the summit earlier in the day, Mr Castro described the US president as an "honest man".

"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."

Cuba is demanding the end to sanctions and the removal of the country from the US list of state-sponsors of terrorism, something the US has hinted it is prepared to do.

As Cuban-US relations are thawing, with other countries at the summit remain fraught, with Venezuela and Ecuador criticising the US.

Ecuadorian President Rafael Correa said the US had failed to live up to its ideals.

"Let's talk about human rights. In Ecuador we don't have torture, the death penalty or extrajudicial renditions."

President Obama responded he always "enjoyed the history lessons" he received, but was the first to acknowledge US faults.

"America does not make a claim to being perfect; we make a claim to being open to change," he said.