The sister of one of the Canadians being held in an Egyptian says her brother is "not in bad shape" considering the circumstances.

But Cecelia Greyson says she hopes her brother John is released soon because he is being held in very difficult conditions.

She says due to the instability in Egypt large numbers of people have been detained so the Canadians are crammed in a cell with several people.

John Greyson, a Toronto filmmaker, and London, Ont., doctor Tarek Loubani were arrested by Egyptian police on August 16 while in Cairo on their way to Gaza.

Canadian officials have said it appears the pair were in the wrong place at the wrong time and were scooped up during the arrests of anti-government protesters.

Cecelia Greyson, who lives in Halifax, says the lawyer for the two detained men will be meeting with an Egyptian prosecutor on Thursday to make the men's case and try to secure their release.

The public prosecutor's office in Cairo says the men face a range of accusations, including threatening security and social peace, belonging to an armed gang and being in possession of firearms, ammunition and explosives.

She says people are working tirelessly to try to free the two men, who can be held for 15 days pending an investigation by prosecutors.

"None of us are getting any sleep, we are all working around the clock to facilitate their release any way we can," said Cecelia Greyson. "It's a tough one, we are never quite sure what is coming around the corner."

An online petition addressed to the Canadian government and the Egyptian Embassy to secure the immediate release of Greyson and Loubani has reached over 70,000 signatories.

Canadian diplomats have visited the pair in prison and the Harper government has expressed its concern with the detentions.