Two Coptic Christian boys in Egypt accused of tearing up a copy of the Koran and of urinating on it have been placed in juvenile detention, a lawyer for the boys said.

A series of incidents involving religious insults, including protests last month over a film made in California that mocked the Prophet Mohammad, have increased tensions between Muslims and Christians in Egypt.

Residents of Marco village in the province of Beni Suef south of Cairo filed complaints against the two brothers, Mina Nadi, 9, and Nabil Nadi, 10, who were then detained on Tuesday and charged with blasphemy, lawyer Gamal Eid said.

Residents of the village and reporters said a passerby had on Monday seen the children ripping up pages of a copy of the Koran and urinating on it in front of the local mosque.

The passerby took the two boys to the local priest to condemn them for the incident, the residents said, but he was not satisfied with what he viewed as the priest's insufficient reprimand and decided to file a complaint to the police.

It was not immediately clear why the children had desecrated the Koran, but some residents said the boys were playing and were not incited by anyone to conduct the act.

Residents said that prosecutors had ordered that the boys be detained for seven days pending an investigation.

Security was stepped up around the village on Tuesday to prevent a potential flare-up of sectarian violence after a group of Muslims g a thered around the police station where the children were being held to demand their prosecution, residents said.

Around 10 percent of Egypt's 83 million people are Christian, many of whom have been concerned about the political rise of Islamists after a popular uprising ousted Hosni Mubarak last year.