CUBA SONIC MYSTERY DEEPENS AFTER FRUITLESS PROBES

HAVANA - Months of investigations into so-called "sonic attacks" on American diplomats in Cuba, which have soured Washington-Havana relations for most of the past year, have turned up nothing.

Cuba said last week it found no evidence to support US claims that several American diplomats in Havana were harmed in what US Secretary of State Rex Tillerson called surreptitious "health attacks."

In a saga seemingly ripped from the pages of a Cold War spy novel, at least 21 US officials and a smaller number of Canadians have received treatment for a variety of symptoms including brain trauma and hearing loss.

Questions linger over whether they are the result of targeted attacks, sabotage, or an accident.

Suspicions were first aroused in late 2016, but Washington waited until August 2017 to announce that several of its embassy employees had fallen victim to mystery health problems that remain unexplained.

US officials have told reporters they believe some kind of inaudible sound weapon was used on its staff either inside or outside their residences in Havana.

The labour union representing US diplomats said their diagnoses of those treated included mild traumatic brain injury and permanent hearing loss.

On September 14, the number of employees affected was 21, with the latest incident being reported last month, US officials said, adding that monitoring of their staff in Havana was ongoing.

A source close to the Canadian embassy told AFP that more than five families had been affected, including several children, but that none of those cases appeared to be serious.

Havana meanwhile said that it had taken additional measures to protect American diplomats and their families.

"The issue is that there are people who are not doing well," the source said.

"And we still do not know why."