Egyptian authorities have indentified the individuals who plotted the Palm Sunday church bombings that killed 46 people in Tanta and Alexandria, a prosecution source told Al-Ahram daily newspaper.
The identity of the suspects has not been made public.
The Islamic State militant group has claimed responsibility for the two deadly blasts that hit the St George Cathedral in Tanta and St Mark's Cathedral in Alexandria on Palm Sunday during prayer services.
On Monday, Egypt's interior ministry said that security forces had killed during a shootout in Assiut seven suspected IS sympathisers thought to be planning more attacks against Coptic Christians.
Copts, who make up about one tenth of Egypt's population of more than 92 million and who will celebrate Easter next weekend, have been targeted by several terrorist attacks in recent months.
In December, a suicide bombing claimed by IS killed 29 worshippers at a Cairo church.
In recent years, Egypt's security forces have been battling a militant insurgency in North Sinai, mostly led by an IS affiliate called Ansar Beit Al-Maqdis, leaving hundreds of security forces killed. The group has also claimed responsibility for several attacks in other parts of the country, including the capital.
Security forces say they have killed hundreds of militants in recent years. Last March, the army said a prominent leader of Ansar Beit Al-Maqdis was killed in a raid in North Sinai.