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 US has not blamed Cuba for the alleged attacks, and the Cuban government has previously denied targeting embassy staff.
Meanwhile, the US expelled 15 Cuban diplomats, saying that Havana had failed to protect its employees, but Cuba said the move was “unjustified”.
The US government also suspended visa processing in Cuba indefinitely.
Speaking in Washington at a meeting of Cubans living in the US, Bruno Rodriguez said the allegations have caused a “serious deterioration in the relationship between both governments and both countries”.
“It’s unacceptable and immoral, from the point of view of the Cuban government, for people to be harmed by a difference between governments,” the minister added.
The reported health problems ranged from mild brain trauma and deafness to dizziness and nausea.
Secretary of State Rex Tillerson said in a statement on October 3: “The decision was made due to Cuba’s failure to take appropriate steps to protect our diplomats in accordance with its obligations under the Vienna Convention. This order will ensure equity in our respective diplomatic operations.”
At least 21 people working at the US’s embassy in Havana have reported health problems, ranging from mild brain trauma and deafness to dizziness and nausea.
Earlier reports suggested sonic attacks were to blame, but nothing has been proven.
Havana denies targeting embassy staff, and the US has not blamed the Cuban government for the suspected attacks.
Rex Tillerson added in his latest statement: “We continue to maintain diplomatic relations with Cuba, and will continue to co-operate with Cuba as we pursue the investigation into these attacks.”
US officials said the expulsions were in protest at Cuba’s failure to protect its diplomats.
Sonic devices may have been used to emit inaudible sound waves that can cause deafness.
On September 1, the US government confirmed that an incident took place as recently as August and that the number of staff reporting problems had increased.
State Department spokeswoman Heather Nauert said: “We can’t rule out new cases as medical professionals continue to evaluate members of the embassy community.”
In a statement, the American Foreign Service Association, which represents US diplomatic and international aid staff, said it had spoken to 10 people who had received treatment.
“Diagnoses include mild traumatic brain injury and permanent hearing loss, with such additional symptoms as loss of balance, severe headaches, cognitive disruption and brain swelling,” the statement said.
The American Foreign Service Association urged the government to do everything possible to help those affected and to “ensure that these incidents cease and are not repeated”.
The statement is the first time that the hearing loss has been described as permanent. It is understood that “mild traumatic brain injury” could include concussion or headaches.
The State Department is yet to blame anyone for the incidents.
The US mission in Cuba was reopened as a full embassy in 2015 following 50 years of hostilities between the two countries.