'No one should be fooled' by Cuba constitution vote: US Secretary Pompeo

US Secretary of State Mike Pompeo on Tuesday dismissed a referendum in Cuba on a new constitution that affirmed the central role of socialism, calling it stage-managed "political theatre" rather than a democratic vote.

"No one should be fooled by this exercise, which achieves little beyond perpetuating the pretext for (the) regime's one-party dictatorship," Pompeo said in a statement.

"The entire process has been marked by carefully managed political theatre and repression of public debate," he said.

Pompeo denounced Cuba for detentions of protesters ahead of the vote, including what he said was confiscation of phones.

"We strongly condemn these attempts to silence peaceful protests, which show that Cuba's leaders fear the Cuban people," he said.

Cuba said that more than 86 per cent of voters in Sunday's referendum approved a constitutional reform that cements the role of socialism on the island. 

In a rarity, Cubans had the option to vote no and the banned opposition -- which generally calls for abstention -- pushed for a rejection.

The referendum comes as the United States ramps up pressure on the communist island, with Pompeo studying whether to allow Cuban exiles to sue in US courts over confiscated property.

Former President Barack Obama had moved to reconcile with Cuba, saying that a half-century of efforts to oust Fidel Castro and his successors had failed and isolated the United States.