President Barack Obama
President Barack ObamaFlash 90

Republicans were left steaming on Tuesday, after President Barack Obama shook the hand of Cuban leader Raul Castro at the memorial ceremony in Johannesburg for late South African leader Nelson Mandela, with one senior lawmaker likening the act to appeasement of the Nazis, according to AFP.

A White House official said the handshake was not "pre-planned," but that did not stop Republicans from assailing Obama for greeting an iron-fisted ruler.

"It gives Raul some propaganda, to continue to prop up his dictatorial, brutal regime, that's all," said Senator John McCain.

McCain said it was a mistake to "shake hands with somebody who is keeping Americans in prison."

Jailed American contractor Alan Gross this month marked four years in prison in Cuba, after his arrest and conviction there for distributing communications equipment to Jewish groups.

"What's the point?" McCain said when asked by AFP if Obama should have made the gesture.

"Neville Chamberlain shook hands with Hitler," he pointed out.

Senator Marco Rubio, whose parents left Cuba three years before Raul's brother Fidel Castro took power, offered a more measured reaction.

Obama "should have asked him about those basic freedoms Mandela was associated with that are denied in Cuba," Rubio told ABC News.

Congresswoman Ileana Ros-Lehtinen also criticized the handshake and lectured Secretary of State John Kerry about it, reported AFP.

"Mr. Secretary, sometimes a handshake is just a handshake, but when the leader of the free world shakes the bloody hand of a ruthless dictator like Raul Castro, it becomes a propaganda coup for the tyrant," she told Kerry at a House hearing on Iran.

Asked by Ros-Lehtinen if he felt Cuba was upholding basic human rights for its citizens, Kerry responded "No, absolutely not."

Amid the criticism, independent Senator Bernie Sanders, who identifies as a democratic socialist, praised the handshake as "positive."

"What I hope it means is that we move toward normal trade relations and normal relations with Cuba," Sanders was quoted by AFP as having said.

Senate Democrat Carl Levin dismissed the controversy, saying, "I think there's too much read into handshakes."