Egyptian authorities have arrested six men accused of waving a rainbow flag, a symbol of LGBT pride, during a pop concert in Cairo and are likely to conduct anal examinations on the suspects.

According to the UK's the Independent, the men have been charged with “debauchery” and “promoting sexual deviancy.”

The flag waiving took place during a concert by Lebanese band Mashrou' Laila, whose lead singer, Hamed Sinno, is openly gay. Several countries, including Amman and Jordan, have banned the group from performing. The band said that Egypt could be next.

The men's trial started on Sunday.

Amnesty International called the charges “deplorable.”

“The fact that Egypt's Public Prosecutor is prioritizing hunting down people based on their perceived sexual orientation is utterly deplorable,” said Najia Bounaim, North Africa campaigns director at Amnesty International. “These men should be released immediately and unconditionally – not put on trial.”

“Forced anal examinations are abhorrent and amount to torture,” she added. “The Egyptian authorities have an appalling track record of using invasive physical tests which amount to torture against detainees in their custody.”

Human Rights Watch also called on authorities to free the men.