France's foreign ministry says a Frenchman died while in police custody in the Egyptian capital.
The ministry said Tuesday it was seeking details about the death of the man who Egyptian authorities say was killed by cellmates while in police custody in Cairo.
Egyptian authorities close to the investigation said prosecutors began questioning the Frenchman's cellmates on Sunday after his corpse revealed signs of bodily harm.
Officials have not said if security officers at the downtown Qasr el-Nil police station where the Frenchman died are also being investigated.
The Frenchman was drunk at the time of his arrest on the streets of the upscale Cairo neighborhood of Zamalek, the Egyptian officials said. He was detained after a military-imposed nighttime curfew, according to the authorities.
Despite a handful of curfew breakers and some local cafes that remain open after hours, most of the city's 18 million people have adhered to the military's orders.
The curfew has been in effect across much of Egypt for more than a month following a deadly spike in violence after security forces raided two protest camps organized by supporters of former President Mohamed Morsi, who was ousted by the military amid mass protests on 3 July.
The Frenchman's arrest highlights the strict enforcement of the country's curfew by the military and police, who man checkpoints across the capital. A journalist for the country's flagship state-run newspaper Al-Ahram was shot to death last month by a soldier at a checkpoint outside Cairo.
The tensions and divisions across Egypt over Morsi's ouster have also fueled xenophobia in some cases. Foreign journalists have reported being harassed at times on the streets by residents accusing them of being spies.
Security officials in Egypt have declined to comment on the Frenchman's arrest and death. It is not clear when he was detained, but France's foreign ministry said he died on Friday.
Officials close to the investigation say it is not clear what started the alleged brawl in prison. After his beating, he was transferred to a hospital where he later died.
The officials spoke on condition of anonymity because they were not authorized to speak to the media about the ongoing investigation.
Ministry spokesman Vincent Floreani said French authorities were seeking details from Egyptian officials about the death.
The victim, whom officials did not identify, had been residing in Egypt. Egyptian officials did not disclose details on whether the man had a residency or proper papers on him at the time of his arrest.
Floreani says the victim's family in France has been contacted.
The embassy added that it had asked for clarification from judicial authorities of the circumstances of the man's death and was still waiting for a reply.