FREE now and never miss the top politics stories again. SUBSCRIBE Invalid email Sign up fornow and never miss the top politics stories again. We will use your email address only for sending you newsletters. Please see our Privacy Notice for details of your data protection rights.

At least 25 people have died and 49 more are injured in the blast, with the number expected to rise, according to Egyptian state television. Many of the victims are women and children who were worshipping in the smaller St Peter and St Paul Coptic Orthodox Church attached to the cathedral. There was no immediate claim of responsibility. Exiled Brotherhood officials and home-grown militant groups condemned the attack. Islamic State (ISIS) supporters celebrated on social media. President Abdel Fattah al-Sisi branded the bombing a terror attack. Security sources said at least six children are among the dead as a protest broke out in front of the cathedral. The blast at St Mark's Orthodox Cathedral in the Abbassiya area of Cairo took place during Sunday morning prayers near the section designed for female churchgoers.

A device containing about 20kg (44 pounds) of the explosive TNT had denoted on the women's side of the cathedral, security sources said. Video footage from the scene showed parts of the cathedral reduced to rubble, with shattered windows and a broken roof. Security sources suggest an unidentified woman planted an IED inside a handbag in the cathedral before detonating the bomb remotely, despite heavy security around the building. Egypt's official MENA news agency said a suspect threw a bomb into a chapel close to the outer wall of St Mark's Cathedral.

TWITTER•REUTERS Bomb explosion at Cairo coptic cathedral

EPA Security officials inspect the damage

EPA Blood stains and belongings of victims seen inside the St Peter and St Paul Coptic Orthodox Church

TWITTER Huge plumes of smoke are seen coming out of St Mark's after the explosion

I saw a headless woman being carried away. Everyone was in a state of shock. We were scooping up people's flesh off the floor Mariam Shenouda

Cathedral worker Attiya Mahrous said: "I found bodies, many of them women, lying on the pews. It was a horrible scene.” Mariam Shenouda said: "I saw a headless woman being carried away. "Everyone was in a state of shock. We were scooping up people's flesh off the floor. "There were children. What have they done to deserve this? I wish I had died with them instead of seeing these scenes.”

AFP GETTY A nun visits the scene as Egyptian security forces inspect the church

REUTERS A relative of one of the blast victims screams at a police officer in front of the cathedral

REUTERS Members of the special police forces stand guard to secure the area around St Mark's

Emad Shoukry, who was inside the cathedral when the blast took place, said: "As soon as the priest called us to prepare for prayer, the explosion happened. "The explosion shook the place... The dust covered the hall and I was looking for the door, although I couldn't see anything... I managed to leave in the middle of screams and there were a lot of people thrown on the ground.” The explosion rocked St Peter and St Paul Coptic Orthodox Church within the cathedral grounds as a Sunday mass was held coinciding with a national holiday in Egypt marking the birth of Islam's Prophet Muhammad.

Another picture of the protest prompted by this morning's attack against a church in #Cairo pic.twitter.com/l6YE5iSBVt — Michael Horowitz (@michaelh992) December 11, 2016

Tensions escalated when Egyptian Prime Minister Sherif Ismail visited the scene as hundreds of protestors chanted in front of the cathedral, with crowds shouting "The people demand the fall of the regime". President Sisi's office condemned the attack as an act of terrorism and declared three days of national mourning. Al Azhar, Egypt's main Islamic centre of learning, also denounced the attacks. The cathedral is the home of the Coptic Orthodox Church in Egypt and home to its leader, Pope Tawadros II of Alexandria. The Coptic Orthodox Church is the largest Christian church in Egypt and the Middle East's biggest Christian community. Coptic Christians, who make up about 10 per cent of Egypt's 90million people, have long complained of discrimination under successive Egyptian leaders. The Foreign Office has warned British tourists in the areas to “remain vigilant at all times and follow the advice of local security officials.”

Coptic Pope Tawadros II cut short a visit to Greece after learning of the attack. Coptic officials said they would not allow the bombing to create sectarian differences. Hani Bakhoum, undersecretary of the Coptic Catholic Patriarchate told Egyptian state television: "We will not allow the terrorist to threaten our national unity with Muslims.” Coptic priests and church officials met with Egyptian security forces to inspect the damage. Bishop Suriel tweeted: “So far 24 martyrs and 36 injured in St Peter Church bomb blast in Cathedral complex. Lord protect your people and have mercy on us! “I’m on my way to the St Peter Church, site of the bomb blast to support the people there. Heartbroken but the Lord is near.”

AFP GETTY Security forces inspect the damage

AFP GETTY The bomb went off as churchgoers attended a Sunday mass

TWITTER At least five people have been killed and ten injured in the blast

TWITTER Ambulances rushed victims to hospitals following the explosion during Sunday prayers

Egyptian authorities have closed roads around the cathedral as traffic in the area comes to a standstill. Ambulances have rushed to the scene and Demerdash Hospital, where many of the victims have been taken, has put out an appeal for blood donors. There was no immediate claim of responsibility, however some supporters of Islamic State celebrated the attack on social media.

TWITTER Eyewitnesses posted images of the cathedral reduced to rubble

FACEBOOK St Mark's Coptic Cathedral has been destroyed in the blast

"God is great, God is great, God is great," one wrote on Telegram messenger. "God bless the person who did this blessed act," wrote another, also on Telegram. Interior minister Magdi Abdel-Ghaffar and Cairo's security chief both inspected the scene. The explosion happened at around 10am local time (8am GMT).

ANADOLU St Mark's Cathedral is the seat of Coptic Orthodox Pope Tawadros II

I'm on my way to the St Peter Church, site of the bomb blast to support the people there. Heartbroken but the Lord is near. — Bishop Suriel (@BishopSuriel) December 11, 2016

So far 24 martyrs and 36 injured in St Peter Church bomb blast in Cathedral complex. Lord protect your people and have mercy on us! — Bishop Suriel (@BishopSuriel) December 11, 2016

It is not the first time St Mark’s has been hit with violence. Two people were killed outside the cathedral in 2013 while mourning the deaths of four Coptic Christians killed in a clash with local residents. On Friday, two roadside bombs - one in Cairo and one north of the capital - killed six policemen and wounded six others.

The St Mark's Cathedral is perhaps the prominent symbol of Egypt's Coptic Community. https://t.co/owNhJIS2LM — Daniel Nisman (@DannyNis) December 11, 2016

Disturbing how attacker managed to infiltrate, plant, and detonate a large bomb inside St Marks entirely undetected. Security there is tight — Daniel Nisman (@DannyNis) December 11, 2016