Coffins arrive for the funeral of those killed in a Palm Sunday church attack in Alexandria, Egypt (AP/Samer Abdallah)

Egyptian churches in the southern city of Minya have cancelled Easter celebrations in mourning for 45 Coptic Christians killed in the bombings of churches in two cities during Palm Sunday ceremonies.

The Minya Coptic Orthodox Diocese said that celebrations will be limited to the liturgical prayers "without any festive manifestations".

Minya province has the highest Coptic Christian population in the country.

Sunday's bombings, claimed by the Islamic State group, are the latest escalation by the extremist group, which recently vowed to step up its attacks against Egypt's embattled Christian minority.

Egypt's President Abdel Fattah el-Sissi declared a three-month state of emergency following the attacks.

Egypt's unicameral chamber preliminarily approved amendments to a set of laws on Monday aimed at speeding up the trials of those charged in terrorism-related cases.

Following the attacks, Mr el-Sissi ordered the formation of a new body called the Supreme Council to Combat Terrorism and Fanaticism.

IS claimed responsibility for the December bombing of a church adjacent to Saint Mark's Cathedral in Cairo, one of the most symbolic religious sites for Egyptian Copts. That explosion killed 30 worshippers and injured dozens.