Reuters Church events are cancelled and only prayers will be held, it says.
Egypt’s government imposed a three-month state of emergency following the bombings in Alexandria and the Nile Delta city of Tanta on Palm Sunday.
Meanwhile, officials have named two of the suicide bombers who they say had links to militant cells.
One has been identified as Mahmoud Hassan Mubarak Abdullah, who was born in 1986 in the southern province of Qena and had been a resident of the north-eastern Suez province, the interior ministry said.
Reuters He used to work for a petroleum company and was linked to a cell that carried out the attack on a Cairo church last December, in which 25 people were killed, it added.
The suspect blew himself up after being stopped by police at the gates of St Mark’s Cathedral in Alexandria, where Coptic Pope Tawadros II led a Palm Sunday service.
On Thursday, the authorities said they had also identified the suicide bomber who attacked the Tanta church.
“DNA tests carried out on the family of a fugitive member and the remains of the suicide bomber… made it possible to identify him as Mamduh Amin Mohammed Baghdadi, born in 1977 in Qena province, where he lived,” an interior ministry statement said.
The ministry said he was also a member of a “terrorist” cell, and was arrested along with three other members of a the cell.
Earlier they named 19 people suspected of having links to the attacks and offered a reward of 100,000 Egyptian pounds ($5,500; £4,400) for any information leading to their arrests. They are now reported to have increased the reward to 500,000 Egyptian pounds ($27,500; £22,000).
So-called Islamic State (IS) said it was behind both explosions.
EPA Easter celebrations on Saturday night would be limited to Masses to mourn the victims of the attacks, Bishop Emmanuel Ayad of Luxor was quoted by the state-run news agency Mena as saying.
Decorations and the traditional handing out of sweets to children by the Coptic Pope will also be cancelled, AFP reports.
The attacks on Christians, who make up about 10% of Egypt’s population, raised security fears ahead of a visit to Cairo by Pope Francis, the head of the Roman Catholic Church, scheduled for 28 and 29 April.
In a visit to Pope Tawadros II, President Abdul Fattah al-Sisi vowed to hunt down those responsible for the bombings.
