A victim is seen on a stretcher after a bomb went off at a Coptic church in Tanta, Egypt, April 9, 2017. (Xinhua/Reuters Photo)
The terrorist bomb attacks killed at least 43 people and injured over 130 others, according to local media.
"The secretary-general expresses his deep sympathies to the families of the victims and to the Government and people of the Arab Republic of Egypt," said a statement issued here by the spokesman of the secretary-general.
"He wishes a quick recovery to those injured and hopes that the perpetrators of this horrific terrorist act will be swiftly identified and brought to justice," the statement said.
The Islamic State has claimed responsibility for the two church bombings, the group's news agency Amaq said.
The 15-nation Security Council, in a separate press statement issued here Sunday, "condemned in the strongest terms the heinous and cowardly terrorist attacks" in north Egypt, and they expressed their deepest sympathy and condolences to the families of the victims and to the government of Egypt and they wished a speedy and full recovery to those who were injured.
"The members of the Security Council reaffirmed that terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security," the statement said.
"The members of the Security Council underlined the need to bring perpetrators, organizers, financiers and sponsors of these reprehensible acts of terrorism to justice and urged all states, in accordance with their obligations under international law and relevant Security Council resolutions, to cooperate actively with the government of Egypt and all other relevant authorities in this regard," said the council statement.
Meanwhile, the council members "reiterated that any acts of terrorism are criminal and unjustifiable, regardless of their motivation, wherever, whenever and by whomsoever committed," the statement said.
"They reaffirmed the need for all States to combat by all means, in accordance with the Charter of the United Nations and other obligations under international law, including international human rights law, international refugee law and international humanitarian law, threats to international peace and security caused by terrorist acts," said the statement.
The first explosion occurred about 09:30 local time at St. George's Church in the Nile Delta city of Tanta, about 90 kilometers north of the capital Cairo.
Hours later, a second explosion occurred at the gates of St. Mark's Cathedral in the coastal city of Alexandria.
Coptic Christians make up about 10 percent of Egypt's population. They have largely coexisted peacefully with the majority-Muslim public for centuries.
Toward the end of 2016, at least 29 people were killed and 31 wounded in an explosion that targeted the Cathedral of Saint Mark in the Abbasia district in Cairo.