A higher number of US and Canadian diplomats along with their families are believed to have been attacked by a mystery sonic weapon in Havana, Cuba, than initially believed, the media reported.
More than 10 US diplomats and family members have received treatment after months of harassing attacks, which began in November 2016 and stopped earlier this year, US government officials familiar with the matter told CNN on Sunday.
Two US diplomats who were treated in the US suffered long-term injuries including hearing loss as a result of the attacks and were unable to return to Cuba.
Additional diplomats opted to leave their assignments in Cuba early, as a result of the harassment, the officials said.
In June, five Canadian diplomats and family members reported experiencing symptoms consistent with the attacks, the officials told CNN.
In some of the attacks, a sophisticated sonic weapon that operated outside the range of audible sound was deployed either inside or outside the residences of US diplomats living in Havana, according to the officials.
The weapon caused immediate physical sensations including nausea, headaches and hearing loss.
Other attacks made a deafeningly loud sound similar to the buzzing created by insects or metal scraping across a floor, but the source of the sound could not be identified.
Some of the diplomats were attacked by the mystery weapon late at night in their homes while they were asleep, the officials added.
The sophistication of the attack has led US officials to suspect a third country's involvement, CNN reported.