A French citizen arrested for violating an army curfew was beaten to death in a Cairo jail cell late Monday night, on the same day that two Canadians held without charge for more than a month began a hunger strike — a grim pairing of events that drew attention both to the dysfunctional Egyptian police force and to rising xenophobia in a country whose economy once relied largely on its booming tourism sector.

The dead man’s name was not publicly released on Tuesday, but a report by the French news agency Agence France-Presse said he had been detained in the upscale island neighborhood of Zamalek on Monday while walking in the street after a nighttime curfew imposed by the military. Soldiers discovered that his visa was no longer valid, arrested him and took him to the Qasr al-Nil police station, a major police facility in downtown Cairo, where he was later beaten to death by other prisoners in a crowded jail cell.

Six of his cellmates are being investigated for “bodily harm resulting in death,” according to Agence France-Presse, which reported that his death was caused by “internal hemorrhaging” and a skull fracture. A report by The Associated Press said that the man was drunk at the time of his arrest and that, although he was beaten inside the jail cell, he was not declared dead until he was taken to a hospital later.

The man died on the same day that supporters of two Canadians arrested and held without charge since Aug. 16 announced that the men, Tarek Loubani and John Greyson, would begin a hunger strike “to protest the arbitrary nature of their detention by Egyptian authorities.”

In the Egyptian legal system, prisoners can be held without charge for 15 days at a time, but their detention can be repeatedly renewed for additional 15-day periods. In a statement, Mr. Greyson’s sister, Cecilia Greyson, cited the specter of indefinite detention without charge as part of the rationale behind the hunger strike.

“We can only imagine the anguish that John and Tarek feel after realizing that their detention could be extended for so long in what can only be described as an arbitrary process that lacks any credibility,” she said. “We know that they did not take the decision to begin a hunger strike lightly, and we want them to know we will do everything we can to support them and get them home soon.”

The two men were arrested during riots in Cairo on Aug. 16 near the Ramses Hilton, a towering hotel in the city center, when they stopped to ask police officers for directions to the hotel after the 7 p.m. curfew. Egyptian prosecutors have accused them of “participating with members of the Muslim Brotherhood” in an armed assault on a police station and “taking part in bloody crimes of violence.”

Supporters of Mr. Loubani and Mr. Greyson call those charges absurd. The men were in Cairo as part of a trip to the Gaza Strip, where Mr. Loubani, a respected emergency room physician and professor of emergency medicine at Western University in London, Ontario, intended to provide training to Palestinian doctors as part of an exchange program he helped establish. Mr. Greyson, a professor at York University in Toronto and a well-known film and television director, accompanied him to document the trip to Gaza for a possible film about Mr. Loubani’s work.

The detention of the two men has been widely condemned. Amnesty International has called for their release, as did a number of artists at the Toronto International Film Festival last week, including the filmmakers Alex Gibney and Sarah Polley and the writer Michael Ondaatje. In late August, some of Mr. Greyson’s students posted a video appeal to YouTube calling for their professor and Mr. Loubani to be released.

Robert Mackey contributed reporting.