Egypt's public prosecutor ordered on Sunday the detention of 10 suspects from a cell reportedly affiliated with the Hasm terrorist group for a duration of 15 days pending investigations.
The High State Security Prosecution accused the 10 of joining an illegal group that calls for the suspension of law and constitution, obstructing duties of state institutions, and attacking personal freedoms.
The suspects are also accused of attacks against state institutions and inciting violence against Christian citizens, their properties and worship houses; they are also accused of using terrorism as a tool to disrupt public order and of endangering society.
The 10 detainees were captured during three simultaneous raids on Saturday on terrorist hideouts in the governorates of Fayoum, Giza and Qaloubiya, and found in possession of weapons and ammunition.
The arrests come one day after a gunman killed several people in a terrorist attack on a Coptic church in Helwan, south of Cairo, which left nine killed and four injured, before the attacker was shot and captured by police.
Friday's attacker in Helwan attempted to drive through a security checkpoint outside the Mar Mina church while armed with a machine gun, ammunition and a bomb that he intended to detonate in the church. Before heading to the church where he shot dead seven people, including a policeman, the assailant killed two people when he opened fire on a shop.
On Saturday Egypt's interior ministry said it had killed three Hasm members during the raid on the terrorist hideout in Giza, explaining that the ministry uncovered a plot "to commit hostile actions that target touristic and other vital facilities, as well as police and armed forces, during Christmas celebrations in an attempt to cause instability and portray a negative image of the security situation in Egypt."
The ministry said the 10 suspects apprehended on Saturday were also involved in a July 2017 attack on security forces in Fayoum, 60 km (40 miles) south of Cairo, which left one security personnel killed and another injured.
"Information revealed that those  arrested received training on using arms and manufacturing explosives at a location in Egypt's Western Desert in the Fayoum governorate, where plotters had listed a number of touristic and security spots in preparation for a planned Christmas attack, following the orders of a fugitive Muslim Brotherhood figure in Turkey," Saturday's statement reads.
Hasm was founded in 2016 and has carried out a number of deadly attacks on security forces.
Police have deployed 230,000 personnel to protect churches, parks and other vital public institutions during the Christmas season, as Egyptian Coptic Christians, who make up around 10 percent of the country's 93 million population, prepare for Christmas on 7 January.
Dozens of Christians have been killed in terrorist attacks on churches and congregations in recent years.