Cuba accused the US of obstructing its probe into mysterious health attacks on American diplomats, claiming its investigators were denied access to the victims and their medical records.
At least 24 US embassy staff in Havana were sickened by a mysterious ailment in the alleged attacks, which began last year and continued until at least August.
The US - which has not directly blamed Cuba for the attacks but has emphasised its responsibility to ensure the safety of foreign diplomats in its territory - has suggested they may have been carried out using a covert acoustic device.
“US authorities have said the responsibility lies with Cuba to investigate the affair and decide on the case, but has failed to play their part as the affected country,” said lieutenant-colonel Francisco Estrada, a Cuban senior interior ministry official, speaking on a documentary that aired on state television.
He added Cuban investigators were being denied the opportunity to be able to speak to experts, witnesses and victims.
The affair has strained diplomatic ties between the two countries, which were only fully restored in 2015 after a half-century Cold War breakdown.
The most recent attack was at the end of August, according to the state department.
Those affected have exhibited physical symptoms including hearing loss, cognitive issues, and difficulty sleeping.
In response, the US withdrew more than half the personnel from the US embassy in Cuba and ordered the expulsion of 15 Cuban diplomats in the US.
On Thursday, the US said it had designated career diplomat Lawrence Gumbiner as the new chief of its Cuba embassy.
The previous charge d’affaires, Scott Hamilton, left Cuba earlier this month after Washington ordered the evacuation of all non-essential staff and all relatives, in order to remain with his family.
Gumbiner will arrive at a time of heightened tensions between the old Cold War foes.
The tensions over the attacks came after Trump said in June he wanted to partially roll back the historic detente between the US and Cuba, ordering tighter restrictions on travel and trade with the island.
These have yet to be unveiled.
Gumbiner, a lawyer, has served for the past three years as deputy chief of mission at the US embassy in Lima, Peru, according to the website of the US
embassy in Havana.
Before that, he was deputy permanent representative at the US Mission to the Organisation of American States.
He has previously held embassy positions in Bogota, Tel Aviv and San Jose.
