Egypt's public prosecutor has detained a disgraced monk on charges of killing a bishop at a desert monastery, his lawyer said on Saturday, in a case that has rocked the Coptic community, the Middle East's biggest Christian minority.

The killing last month of Bishop Epiphanius, a 64-year-old scholar who had led the Abu Makar or St Macarius Monastery in Wadi Natroun, an area some 110 km (68 miles) northwest of Cairo, prompted the church to impose strict new measures on its clergy.

Lawyer Ameer Naseef told Reuters that an Alexandria prosecutor on Friday charged Wael Saad, a monk who was known as Isaiah al-Makari before he was stripped of his religious title, with the July 29 killing.

Officials from the prosecutor's office were not immediately available, but judicial sources confirmed the report.

'The prosecution's decision came yesterday, on Friday, and it (the prosecution) asked that his remand be renewed on time,' Naseef told Reuters, adding that this would be done on Sunday.

Christians in Egypt make up an estimated 10 per cent of its roughly 96 million population.

The church had earlier said that Saad had been investigated over alleged long-standing violations of his duties as a monk, but denied that he had been suspected of involvement in Bishop Epiphanius' killing.

The case has prompted the head of the Coptic church, Pope Tawadros II, to launch sweeping measures to combat what some Christian figures have described as violations of the principles of poverty and chastity.

The measures include a freeze on accepting new monks, a ban on monks leaving monasteries without official permission and a ban on clergy using social media.

Tawadros II and other clerics have since closed down their social media accounts.