The Dominican Republic is a popular destination for winter sunseekers from across North America. Photo: Getty Images

Christine Sauvé and Alain Noël died in their sleep the night of 25 December, Sauvé's brother Gilles Sauvé Jr told the Canadian Broadcasting Corporation (CBC) in an interview.

Sauvé says the cause of the couple's deaths is still unknown, and that their bodies were found by their son, who was on vacation with them.

Local authorities are investigating, he said, and they have told him to expect autopsy results in 45 days.

Sauvé told the CBC that his sister had called him the night before, saying she was feeling dizzy and had visited the hospital.

She had bloodwork done and was supposed to have more scans the next day, he said.

"In the end, it didn't come to that," he said.

Global Affairs Canada, the government's global outreach arm, told the BBC that it is aware of the deaths and is in touch with officials in the area.

"Canadian officials are providing consular assistance and are in contact with local authorities to gather more information," it said.

The couple had been saving to travel the world, Sauvé said.

"It was their retirement plan," he added. "Like snowbirds."

He is now in the Dominican Republic speaking to authorities and trying to obtain death certificates to ultimately repatriate the bodies to Canada, he said.

"What's very difficult is that we're not in Quebec [and it's] the holiday season," he said. "Everything is closed, including the embassies. We're trying to get things done, but everything is progressing very slowly."

The BBC has reached out to the Canadian embassy in Santo Domingo but has not heard back.