The Egyptian Coptic Coalition has demanded an investigation into an incident which took place on Monday night, when a group of Salafist Muslims occupied a parcel of land owned by Egypt's Coptic Orthodox Church in Cairo's Shubra Al-Kheima district.
After illegally entering the land, the Salafists put up a sign bearing the words 'Al-Rahma Mosque' and performed Islamic prayers inside the premises.
The crowd only left when the church authorities informed the interior ministry.
Security forces were able to take down the sign on Tuesday morning.
The Egyptian Coptic Coalition group, in a statement issued Tuesday, held President Mohamed Morsi responsible for dealing with the incident and urged him to impose harsher punishments for such attacks. It also called for an investigation into Monday's incident immediately.
The group demanded authorities put in place strict laws that prohibit the appearance of "extremist" religious preachers whom the group accuses of spreading sectarianism.
The group also demanded the appointment of an "impartial' security official in each governorate to intervene immediately in cases of attacks on citizens or property on the basis of their religion.
In an earlier statement, Egypt's Maspero Copts Youth United also denounced the incident, attributing it to the state's failure to respond to earlier incidents of sectarian violence, including the burning of Christian churches which happened in the wake of last year's Tahrir Square uprising.
Egypt's Copts, estimated at between 10 and 15 per cent of the total national population, have long demanded legislation allowing them to build churches freely and without bureaucratic restrictions.
Egypt's new Coptic Pope Tawadros II, elected on Sunday, is expected to work towards achieving this end.