Egyptian authorities have arrested at least 22 people in the past four days as part of a campaign against LGBT people, Amnesty International says.
Thirty-two men and one woman have now been detained since rainbow flags were displayed at a pop concert in Cairo last month, according to activists.
an*l examinations have been reportedly carried out on five of those arrested.
The flag-raising provoked a public outcry and prompted the public prosecutor to order an investigation.
Homosexuality is not explicitly criminalised under Egyptian law.
But the authorities routinely arrest people suspected of engaging in consensual homosexual conduct on charges of "debauchery", "immorality" or "blasphemy".
The raising of rainbow flags at the concert by the Lebanese band Mashrou' Leila - whose lead singer is openly gay - on 22 September was a rare public show of support for the LGBT community in the conservative Muslim country.
Three days later, after images went viral, Public Prosecutor Nabil Sadek ordered State Security prosecutors to investigate an "incident" that "incited homosexuality".
On Sunday, six men were charged in connection with the flag-raising and went on trial alongside at least 10 others arrested last week, according to the Egyptian Initiative for Personal Rights, a local human rights organisation. A verdict in their trial is expected on 29 October.
A woman suspected of raising a rainbow flag at the concert has also been charged with "promoting sexual deviancy" and "habitual debauchery".
On Monday, Amnesty reported that a seventh man had also been detained in the city of Damietta in relation with the flag incident, and that six other men had been detained in Cairo in recent days for promoting "habitual debauchery" through online dating applications. Four further arrests took place in Giza, it said.
A 19-year-old man arrested a day after the concert was meanwhile sentenced last week to six years in prison after being convicted of "debauchery", Amnesty added, and four other men were being held at Cairo police stations.
The Forensic Medical Authority has carried out an*l examinations on at least five of those arrested, according to Amnesty. Such procedures are used regularly in prosecuting homosexual sex in Egypt.
"Forced an*l examinations are tantamount to torture - there is no scientific basis for such tests and they cannot be justified under any circumstances," said Najia Bounaim, Amnesty's North Africa campaigns director.
"The scale of the latest arrests highlights how dangerously entrenched homophobia is within the country. Instead of stepping up arrests and carrying out an*l examinations, the authorities must urgently halt this ruthless crackdown and release all those arrested immediately and unconditionally."
Members of Mashrou' Leila, whom the Egyptian Musicians Syndicate has vowed to bar from performing, said the crackdown had left them "heartbroken".
A statement issued on Monday evening said they had initially remained silent on the advice of activists for fear of "further inflaming the situation", but that it had since become apparent "that the state apparatus is hell-bent on executing the most atrocious of human rights violations".
"We denounce the demonisation and prosecution of victimless acts between consenting adults," it added. "It is sickening to think that all this hysteria has been generated over a couple of kids raising a piece of cloth that stands for love."