WASHINGTON — The Canadian government said Thursday that at least one Canadian diplomat in Cuba also has been treated for hearing loss following disclosures that a group of American diplomats in Havana suffered severe hearing loss that U.S. officials believe was caused by an advanced sonic device.

Global Affairs Canada spokeswoman Brianne Maxwell said Canadian officials “are aware of unusual symptoms affecting Canadian and U.S. diplomatic personnel and their families in Havana. The government is actively working — including with U.S. and Cuban authorities — to ascertain the cause.”

Canada helped broker talks between Cuba and the United States that led to restored diplomatic relations.

In the fall of 2016, a series of U.S. diplomats began suffering unexplained losses of hearing, according to officials with knowledge of the investigation into the case. Several of the diplomats were recent arrivals at the embassy, which reopened in 2015 as part of President Barack Obama’s reestablishment of diplomatic relations with Cuba.

Some of the U.S. diplomats’ symptoms were so severe that they were forced to return early to the United States, officials said. After months of investigation, U.S. officials concluded that the diplomats had been attacked with an advanced sonic weapon that operated outside the range of audible sound and had been deployed either inside or outside their residences.