Human Rights Watch has urged Egypt to free seven men accused of "inciting debauchery" after they were filmed attending an apparent gay marriage on a Nile riverboat.
The New York-based watchdog on Tuesday said prosecutor general Hisham Barakat had ordered the men detained and "physically examined" after they were seen in the video that was posted on the Internet.
The seven were arrested on Saturday and remanded in custody for up to four days, accused of "incitement to debauchery" and "publishing indecent images," the official MENA news agency said at the time.
Homosexuality is not included in a list of sexual offences explicitly outlawed by Egyptian law, but it can be punished under several different statutes on morality.
"One of the men involved in the incident reportedly phoned in to an Egyptian television news programme to deny that he was homosexual or that the filmed event was a gay marriage," HRW said.
The seven were arrested after appearing in the video that was posted on YouTube showing two men celebrating a marriage ceremony and exchanging rings surrounded by friends.
HRW said they had undergone "forensic anal examinations," which the authorities have used repeatedly in cases of allegedly homosexual misconduct.
"Over the years, Egyptian authorities have repeatedly arrested, tortured, and detained men suspected of consensual homosexual conduct," HRW's Graeme Reid was quoted as saying.
"These arrests represent another assault on fundamental human rights and reflect the Egyptian government's growing disdain for the rule of law."
As well as facing widespread public prejudice, Egyptian homosexuals have in the past been jailed on charges ranging from "scorning religion" to "sexual practices contrary to Islam."
In April, a court sentenced four men to up to eight years in prison under anti-debauchery laws targeting homosexuality.