International condemnations followed an attack by gunmen on a North Sinai mosque on Friday during prayer that killed at least 200 worshippers.
According to Russian news agency TASS, Russian President Vladimir Putin has sent a telegram of condolences to President Abdel-Fattah El-Sisi regarding the attack.
"The killing of civilians during the mosque prayer strikes one with its cruelty and cynicism. We can see once again that the human morality concept is totally alien to terrorists," Putin noted according to TASS, adding that his country is ready to boost cooperation with Egypt in the fight against international terrorism.
Boris Johnson, the UK Foreign Secretary, wrote on Twitter: "Deeply saddened by the abhorrent attack on a mosque in North Sinai, #Egypt. My sincere condolences to all those affected by such a barbaric act,"
In an official statement, the UK's envoy to Egypt, John Casson, also denounced the attack on Al-Rawda mosque in western Arish.
"I am disgusted by the evil attack that killed & injured so many Egyptians in Sinai today. On behalf of the UK my deep condolences to all involved. These attacks on people praying in mosques & churches only strengthen our determination to stand together, & defeat terrorism & hate," Casson tweeted.
Pope Francis condemned the "wanton act of brutality" against innocent people in a message sent on his behalf by the Vatican Secretary of State, Italian Cardinal Pietro.
He said he is “profoundly grieved to learn of the great loss of life caused by the terrorist attacks on the Rawda Mosque in North Sinai,” while expressing solidarity with the Egyptian people.
The French ambassador in Cairo, Stéphane Romatet, also condemned the attack, referring to it as "barbaric and ignominious."
"Egypt is in mourning and France stands beside it," Romatet said on his Twitter account.
Bahrain also denounced the attack “in the strongest terms,” with the Bahraini foreign ministry stressing its supportive stance with Egypt against terrorism and extremism.
In an official statement, the US embassy in Cairo described the attack as an "unconscionable act of cowardice and hate."
"As Egypt battles the scourge of terrorism, the United States stands committed to the safety and security of Egypt and its people," the statement read.
France has also condemned the attack, according to MENA.
"France condemns this low attack that has submerged the whole country in mourning," Foreign Minister Jean-Yves Le Drian said.
The minister said France will continue forming a joint front with Egypt to combat terrorism.
President Abdel-Fattah El-Sisi has also received condolences letter from his Italian counterpart Sergio Mattarella, stressed his country’s support for Egypt in the fight against terrorism, MENA reported.
"In the joint struggle against terrorism and religious extremism, who are the main enemies of freedom of worship, Egypt can always count on the sincere support from Italy," Mattarella said.
The ambassador of the European Union to Egypt, Ivan Surkoš, has also condemned the "brutal terrorist attack against innocent civilians,” stressing that the EU supports Egypt in combating terrorism, MENA reported.
Both King Salman and Crown Prince Mohamed bin Salman of Saudi Arabia have sent condolence letters to El-Sisi, MENA reported.
King Salman said that his country "stands by Egypt and its people in combating terrorism, and its attempts to establish the security and the stability of Egyptian people," MENA reported.
"I condemn this evil terrorist act that targeted secured innocents in a house of God," the king reportedly said.
Palestinian President Mahmoud Abbas strongly condemned the attack, saying in a statement that the Palestinian people and leadership stands beside Egypt in its war on terrorism.
Turkey also condemned the attack.
"I strongly condemn the terrorist attack in Sinai region of Egypt that took lives of many innocent civilians. I convey my condolences to the families of those who were killed and to the brotherly people of Egypt; I also wish speedy recovery to the wounded," Turkey's Foreign Minister Mevlüt Çavuşoğlu wrote on Twitter.
Ukraine, Tunisia, Oman, Kuwait, Iraq, Libya, Mauritania, Bahrein, Sudan and Yemen also condemned the terror attack.
At least 125 worshippers were also injured in the attack that took place after gunmen fired heavily on worshippers after improvised explosive devices were detonated at the mosque after Friday prayers.
The attack is one of the deadliest such against civilians in the country in recent years.
The Egyptian president’s office has announced a three-day mourning period.