CAIRO — Two Coptic Christian boys have been detained by the authorities on charges that they defiled the pages of a Koran, the latest in a spate of recent cases involving accusations that people have insulted Islam.

The boys, ages 9 and 10, are being held in juvenile detention in the village of Ezbet Marco, south of Cairo, according to Ishak Ibrahim, a researcher with the Egyptian Initiative for Personal Rights who is investigating the case. They were detained last Sunday, when the imam of the local mosque claimed that he saw the children tearing the pages of a Koran.

Other news reports said the boys were accused of urinating on the Koran pages.

The charges seemed likely to add to growing anxieties in Egypt about free speech rights, the sway of hard-line Islamists and the status of the country’s Christian minority, which fears an erosion of rights under an Islamist government. It also recalled the recent arrest in Pakistan of a Christian girl who was accused of burning Muslim texts in a case that drew attention to the use of blasphemy laws to intimidate minorities.

Mr. Ibrahim said there had been at least 17 cases involving the charge of contempt of religion since the 2011 uprising that deposed President Hosni Mubarak of Egypt. A flurry of recent cases suggests that the authorities are moving more aggressively to act on such accusations.