A group of 14 Canadian diplomats along with their families is suing the government for C$28 million ($21.1 million) after they succumbed to a mysterious illness in Cuba.
The group says the Canadian government took too long to warn, evacuate and treat them.
In 2018, Canadian and US officials were recalled from Cuba after complaining of dizziness and migraines.
The cause of the illness is unknown, but Canada has discounted the idea of a “sonic attack” on its embassy.
In a statement, the group said: “Throughout the crisis, Canada downplayed the seriousness of the situation, hoarded and concealed critical health and safety information, and gave false, misleading and incomplete information to diplomatic staff.”
According to CBC, staff at the Canadian embassy began experiencing symptoms of the so-called “Havana syndrome” in spring 2017.
Several families were subsequently moved from Cuba, but until April 2018 Canada continued to post new staff to Havana despite warnings from US counterparts who had received similar complaints.
The US withdrew most of its non-essential personnel from Cuba in September 2017 and said 21 embassy employees had been affected.
Last month, Canada said it would be cutting its embassy staff by up to half.
At a news conference in Washington, Canada’s Foreign Affairs Minister Chrystia Freeland said she was aware of the lawsuit.
She said: “I am not going to comment on the specifics, but I do want to reiterate that I have met with some of these diplomats and, as I said to them, their health and safety needs to be our priority.”
Cuba has repeatedly denied any involvement in the incident.
Cuba’s Foreign Minister, Bruno Rodriguez, said US claims were a “political manipulation” aimed at damaging bilateral relations.
The State Department said it was taking the reports seriously, but did not yet know the cause, and warned staff to move to a safe place if they encountered any “unusual acute auditory or sensory phenomena accompanied by unusual sounds or piercing noises”.
One US official was diagnosed with mild brain trauma, the same injury that affected the Cuban embassy staff.
The State Department has warned that US diplomats should alert their mission’s medical staff “if they note new onset of symptoms that may have begun in association with experiencing unidentified auditory sensations”.
It said it had sent a team to Guangzhou and set up a task force to oversee the response to the mystery attacks in China and Cuba.
Cuba has denied targeting embassy staff, and the US has not blamed the country’s government for the suspected attacks.
According to specialists, symptoms of a sonic attack may include dizziness, headaches, vomiting, bowel spasms, vertigo, permanent hearing loss and even brain damage.