Tanta, April 9: Suicide bombers attacked two Coptic churches in Egypt on Palm Sunday, killing at least 40 worshippers and police officers stationed outside, in the deadliest day of violence against Christians in the country in decades.

The Islamic State group claimed responsibility for both attacks in a statement via its Aamaq news agency, having recently signaled its intention to escalate a campaign of violence against Egyptian Christians.

The first explosion occurred about 9.30 at St. George's Church in the Nile Delta city of Tanta, 50 miles north of Cairo, during a Palm Sunday Mass. Security officials and a witness said a suicide bomber had barged past security measures and detonated his explosives in the front pews, near the altar.

At least 27 people were killed and 71 others injured, officials said.

Hours later, a second explosion occurred at the gates of St. Mark's Cathedral in the coastal city of Alexandria. That blast killed 13 people and wounded 21 others, the health ministry said.

The patriarch of the Egyptian Coptic Church, Pope Tawadros II, who is to meet with Pope Francis on his visit to Egypt on April 28 and 29, was in the church at the time but was not injured, the interior ministry said.

Kamil Sadiq Sawiras, a Coptic church official in Alexandria, said a police officer at the church gates had intercepted a suicide bomber, who blew himself up before he could reach the church.

Two police officers and a neighbourhood police chief, Adel El-Rakiby, were among the dead.

The bombings, at the start of the Holy Week leading to Easter, renewed questions about the ability of President Abdel Fattah al-Sisi to protect minority Christians, who make up about 10 per cent of Egypt's 90 million people.

As forensic teams combed through the bloodstained wreckage of the church in Tanta, witnesses told of how a suicide bomber managed to slip through a side door where security officials had been checking congregants with a metal detector as they entered.

Several deacons, lay Christians who help with the service, were among the dead. Remon Emaad said the church had been on alert since the authorities discovered an explosive device nearby last week and defused it.

Soia Williams said that her uncle, Methat Moussa, a retired army officer, had been late to today's service and had gone to the front pews, where the explosion went off. "We can't find his body, just a bloodied identity card," she said.

Egyptian security officials found and defused several other explosive devices at other locations, including at a prominent Sufi Muslim shrine. One bomb had been planted at the Collège Saint Marc, an all-boys school in Alexandria.

Two others were found at the Sidi Abdel Rahim Mosque in Tanta, home to one of the most famous Sufi shrines in the city. The authorities also found two suspected bombs at a local market in the coastal city of Marsa Matruh, state news media reported.

The violence today comes weeks before the visit to Egypt by Francis, in what has been billed as the latest stage of his long-running effort to forge stronger ties with Muslim leaders. But the pontiff will find himself arriving in a country where the government is struggling to protect Christians and where the Islamic State is intent on driving a wedge between the two religions.

In December, an Islamic State suicide bomber killed 28 people in an attack on a chapel in the grounds of St. Mark's Coptic Cathedral in Cairo. In February, hundreds of Christians fled their homes in north Sinai after a concerted campaign of assassination and intimidation in the area.

After the attack in December, the Islamic State said it was escalating a campaign of sectarian bloodshed in Egypt.

The Islamic State has an active affiliate in Egypt, which has claimed numerous other attacks, including the downing of a MetroJet flight in 2015, which killed more than 200 passengers flying from an Egyptian resort to Russia.

Its campaign poses a frontal threat to Sisi, a strongman ruler who has put security at the heart of his legitimacy in Egypt, and who has used his anti-Islamist credentials to win support from Western allies.

In a statement, President Sisi said he had convened a meeting of the National Defense Council, which includes the Prime Minister and commanders of the Egyptian armed forces, in response to the bombings.<>Responding to the attacks from Rome, Francis offered his condolences to the Copts and all Egyptians, and referred to the Coptic patriarch as his "brother".

During his coming trip to Egypt, the Arab world's most populous country, the pontiff is to visit with Sisi; the leadership of the Coptic Orthodox Church; and the grand imam of Al Azhar, a 1,000-year-old mosque and university that is revered by Sunni Muslims.

The grand imam, Sheikh Ahmed el-Tayeb, condemned the attacks today as a "despicable terrorist bombing that targeted the lives of innocents".Relations between Muslim leaders and the Roman Catholic Church became strained under Francis's predecessor, Pope Benedict XVI, who denounced what he called "a strategy of violence that has Christians as a target" after a bombing in 2011 at a church in Alexandria killed at least 23 people.Francis actively sought to rebuild ties with Muslim clerics after becoming pope in 2013, and last year he welcomed the grand imam of Al Azhar in the Vatican.Although the head of the Catholic Church in Egypt, Bishop Emmanuel, told reporters on Friday that the pope's pending journey was a signal that Egypt is safe for visitors, the attacks today were certain to bring new scrutiny on security arrangements for the trip in April.In a Twitter post, a spokesperson for the Egyptian foreign affairs ministry, Ahmed Abu Zeid, said: "Terrorism hits Egypt again."

New York Times News Service