WASHINGTON, United States (AFP) — Cuba’s foreign minister on Thursday accused anyone claiming attacks took place against US diplomats in Havana of “deliberately lying,” echoing comments he made last week in an ongoing dispute.

“It is time the United States tells the truth or presents evidence,” Bruno Rodriguez insisted during a press conference in Washington, referring to incidents which affected the health of at least 24 US embassy officials in Havana, according to the State Department.

“Those who state there have been attacks, deliberate acts or specific incidents causing damage to health are deliberately lying,” he said, adding that so far US authorities “have not presented an atom of evidence” the alleged attacks happened.

US Secretary of State Rex Tillerson earlier described the incidents, which began last year, as “health attacks.” Several Canadian families were also affected.

Washington’s ties with Havana were only fully restored in 2015 after a half-century Cold War breakdown, but have been strained since President Donald Trump took office in January.

Washington has not formally blamed Havana, but in mid-October Trump said that he holds Cuba responsible — and the White House has said it believes the country could bring the attacks to a halt.

“The so-called sonic attacks … are totally false,” Rodriguez said last Saturday in a surprise appearance at a Washington meeting of Cubans living in the United States.

He called the allegations “political manipulation aimed at damaging bilateral relations.”

Both governments opened investigations into the mysterious incidents — which US officials said may have been carried out with some sort of acoustic device.

Cuban experts investigating the case said it “is impossible that only one cause explains the diverse range of symptoms” reportedly experienced by diplomats.

The State Department says the most recent incident was at the end of August, with those affected experiencing hearing loss, cognitive problems, and difficulty sleeping.

On September 29, the United States halved its personnel in Havana and suspended visa services indefinitely.

The White House also expelled 15 diplomats from the Cuban embassy in Washington, arguing Havana did not comply with responsibilities under the Vienna Convention to ensure the safety of diplomats on its soil.