Two international rights groups are calling on Egyptian authorities to halt their crackdown on people suspected of homosexuality following the waving of the LGBT rainbow flag at a recent concert in Cairo.

Human Rights Watch and Amnesty International also urged Egypt on Saturday to call off the anal examination of people detained on suspicion of homosexuality to determine whether they were engaged in same-sex sexual relations. They said the practice amounted to torture, calling it "abhorrent" and scientifically unsound.

Homosexuality is highly taboo in Egypt among Muslims and minority Christians, but it is not explicitly prohibited by law. In practice, authorities prosecute individuals under such charges as "immorality" and "debauchery."

Egypt arrested at least seven people last week after footage of the rainbow flag surfaced on social media.