Cuba’s Foreign Minister Bruno Rodriguez on Saturday said that the United States’ allegations that the country was behind the mysterious attacks on American embassy staff in Havana were “totally false”, the BBC reported. He said the claims were “political manipulation” aimed at damaging bilateral relations.

“It is unacceptable and immoral, from the point of view of the Cuban government, for people to be harmed by a difference between governments,” he said in Washington, adding that the allegations have caused “serious deterioration in the relationship between both governments and both countries”.

The incidents have lately increased tensions between the US and Cuba, who re-opened diplomatic relations in 2015 after half a century of estrangement.

On October 16, US President Donald Trump had said he believed Cuba was responsible for the unexplained “attacks”. The State Department, however, has repeatedly said it does not know what is causing their government workers’ illnesses.

In September, the US had ordered more than half of its diplomats to leave Cuba, a year after they began to describe unexplained health problems. At least 21 of them and their families reported traumatic brain injuries and permanent hearing loss.

The mysterious illnesses

The symptoms of illness have varied from person to person. In addition to hearing loss and concussions, some experienced nausea, headaches and ear-ringing, and some now suffer from problems with concentration and word recall.

Initially, officials suspected sonic attacks, but the Federal Bureau of Investigation and other agencies that searched homes and hotels in Cuba where the incidents occurred found no devices. A Canadian diplomat was also affected, and this has deepened the mystery as relations between Canada and Cuba have been warm.