A Halifax woman whose brother is locked in an Egyptian prison said she’s hoping the prime minister’s involvement will help bring him back home to Canada.

John Greyson, a Toronto filmmaker and university professor, and Tarek Loubani, an emergency room doctor from London, Ont., were arrested in Cairo on Aug. 16.

Cecilia Greyson has been working ever since to help her brother.

It’s “like a waking nightmare,” she said.

"It's sort of like constant nausea. You're constantly worried.”

Loubani and Greyson say they were stuck in Cairo that day because it was difficult to cross into Gaza, and so decided to visit a protest in Ramses Square, five blocks from their hotel.

Cecilia Greyson

Cecilia Greyson said she's "very disappointed" about news that charges may be laid against her brother. (CBC)

On the weekend, the Prime Minister’s Office called for the men’s release.

“In the absence of charges, Dr. Loubani and Mr. Greyson should be immediately released,” read the statement.

"It is a very bold statement for a democratic leader to make that kind of statement,” said Greyson.

“We're hoping it has an impact in Egypt. We're not sure. Obviously it's a new government in Egypt and we don't know the dynamics of the particular regime."

Greyson said she’s hoping continued pressure by the government and supporters will force authorities to back down.

The detained pair are on a hunger strike.

“Every day that they are in detention in this prison is another day that they are in jeopardy. Their physical safety, their physical well being is in jeopardy,” she said.

Greyson said Loubani and her brother are stuck in a small, concrete cell with six other people.

Egyptian authorities said they will remain there for at least another 45 days.