Major stars and filmmakers at the Toronto International Film Festival are throwing their support behind two Canadians who've been imprisoned in Egypt for 25 days, calling for their immediate release.

Canadian director Atom Egoyan presented a statement Tuesday, calling on Egyptian authorities to release filmmaker John Greyson and Dr. Tarek Loubani from the Cairo prison where they are being held.

"We are respectfully asking the Egyptian authorities to release Professor Greyson and Dr. Loubani immediately," he said at a news conference in Toronto.

The statement has been signed by 311 artists, filmmakers and academics from around the world, including Ben Affleck, Danny Glover, Charlize Theron, Willem Dafoe and Paul Haggis, actress Sarah Polley said.

An online petition that also calls for their release has received over 100,000 signatures as of Tuesday afternoon.

Greyson and Loubani were arrested in Cairo on Aug. 16, amid riots that were gripping the Egyptian capital.

Friends of the men say they were en route to Gaza, where Loubani was participating in a training program with doctors at the Al-Shifa Hospital. Greyson, who is a professor of film at York University, was accompanying him to research a potential future film.

Their family members are "extremely concerned" with their safety and well-being, John’s sister Cecilia Greyson said.

"They were simply at the wrong place at the wrong time," she said. "They went into a police station for directions back to their hotel and were detained."

Greyson and Loubani are said to be sharing a jail cell with 38 other people. The cell has only one toilet and one tap. Last week, they were allowed their first 30 minutes of fresh air.

Greyson’s sister said the two men were “completely overwhelmed” when they learned that more than 100,000 people had signed a petition calling for their release.

The Department of Foreign Affairs issued a statement Tuesday saying they remain committed to seeing the two men released.

“Canada remains concerned about the cases of Dr. Loubani and Mr. Greyson and continues to work at the highest levels to confirm the specific charges against them. As we have not yet received confirmation of the charges, Canada calls for their release," the statement said.

In late August a meeting between the men's lawyer and the Egyptian prosecutor was cancelled after the prosecutor failed to appear.

With a report from CTV’s Daniele Hamamdjian