US Secretary of State John Kerry has cancelled a trip to Cuba two weeks before President Barack Obama visits the communist-ruled nation as diplomats haggle over which Cuban dissidents the president

will be allowed to meet.

The back and forth over human rights is another sign of how prickly US-Cuba relations remain despite the restoration of diplomatic ties, and the easing of many travel and trade restrictions, over the last year.

It also highlights a potential problem for Obama’s planned overnight visit on March 21, the first by a sitting president in nearly 90 years, to the former Cold War adversary.

Despite the US push toward normalisation of relations, the government in Havana has done little to ease its limits on free expression or to improve treatment of human rights activists and political dissidents.

President Raul Castro has supported opening the Cuban economy to incorporate free market elements, including private enterprise and private ownership of homes and cars, for the first time since the 1959 revolution that brought the communists to power.

But he has insisted that the political system and the “socialist nature of the revolution” will not change. His Foreign Ministry official for US affairs, Josefina Vidal, has described the US focus on human rights as hypocritical.

Despite that resistance, Obama, in his announcement last month of his two-day trip, said he aims to engage with the Cuban people. Previously, he had said he would not go unless Cuba allowed significant progress on human rights.

“We determine who we meet with in different countries,” Ben Rhodes, Obama’s deputy national security adviser, said February 18. ”And we’ve certainly indicated to the Cubans that this is something the president will be doing on this trip, as he does on other trips.”

Kerry, who flew to Havana in August to reopen the US Embassy, had planned to return this week to lay the groundwork for Obama’s visit. But that trip was cancelled, officials said Thursday, when arrangements could not be finalised.

Kerry “is still interested in visiting in the near future, and we are working with our Cuban counterparts and our embassy to determine the best time frame,” said John Kirby, the State Department spokesman.

Other officials said the new US Embassy, which remains a bare-bones operation, was overwhelmed trying to arrange back-to-back visits by Kerry and Obama.

When US diplomats began negotiations for Obama’s visit, they said any attempt to block him from meeting dissidents would be a deal breaker, according to a White House official who spoke on condition of anonymity because of diplomatic sensitivities.

But political dissidents in Cuba are a varied bunch.

Some are so bitterly anti-Castro, they disapprove of Obama’s rapprochement and might refuse an invitation. Others, known worldwide, are despised by the Cuban government.